diff --git a/core/audits/metrics/interaction-to-next-paint.js b/core/audits/metrics/interaction-to-next-paint.js
index 5ed8bfba5abd..6075e6015811 100644
--- a/core/audits/metrics/interaction-to-next-paint.js
+++ b/core/audits/metrics/interaction-to-next-paint.js
@@ -70,9 +70,7 @@ class InteractionToNextPaint extends Audit {
       return {score: null, notApplicable: true};
     }
 
-    // TODO: remove workaround once 103.0.5052.0 is sufficiently released.
-    const timing = interactionEvent.name === 'FallbackTiming' ?
-        interactionEvent.duration : interactionEvent.args.data.duration;
+    const timing = interactionEvent.args.data.duration;
 
     return {
       score: Audit.computeLogNormalScore({p10: context.options.p10, median: context.options.median},
diff --git a/core/audits/work-during-interaction.js b/core/audits/work-during-interaction.js
index e0839bbdf536..dd01e2742511 100644
--- a/core/audits/work-during-interaction.js
+++ b/core/audits/work-during-interaction.js
@@ -14,7 +14,6 @@ import {taskGroups} from '../lib/tracehouse/task-groups.js';
 import {TraceProcessor} from '../lib/tracehouse/trace-processor.js';
 import {getExecutionTimingsByURL} from '../lib/tracehouse/task-summary.js';
 import InteractionToNextPaint from './metrics/interaction-to-next-paint.js';
-import {LighthouseError} from '../lib/lh-error.js';
 
 /** @typedef {import('../computed/metrics/responsiveness.js').EventTimingEvent} EventTimingEvent */
 /** @typedef {import('../lib/tracehouse/main-thread-tasks.js').TaskNode} TaskNode */
@@ -243,13 +242,6 @@ class WorkDuringInteraction extends Audit {
         metricSavings: {INP: 0},
       };
     }
-    // TODO: remove workaround once 103.0.5052.0 is sufficiently released.
-    if (interactionEvent.name === 'FallbackTiming') {
-      throw new LighthouseError(
-        LighthouseError.errors.UNSUPPORTED_OLD_CHROME,
-        {featureName: 'detailed EventTiming trace events'}
-      );
-    }
 
     const auditDetailsItems = [];
 
diff --git a/core/computed/metrics/responsiveness.js b/core/computed/metrics/responsiveness.js
index 64bd8fb6016a..c1d32802cbb4 100644
--- a/core/computed/metrics/responsiveness.js
+++ b/core/computed/metrics/responsiveness.js
@@ -24,14 +24,10 @@
  * @property {number} interactionId
  */
 /** @typedef {LH.Trace.AsyncEvent & {name: 'EventTiming', args: {data: EventTimingData}}} EventTimingEvent */
-/**
- * A fallback EventTiming placeholder, used if updated EventTiming events are not available.
- * TODO: Remove once 103.0.5052.0 is sufficiently released.
- * @typedef {{name: 'FallbackTiming', duration: number}} FallbackTimingEvent
- */
 
 import {ProcessedTrace} from '../processed-trace.js';
 import {makeComputedArtifact} from '../computed-artifact.js';
+import {LighthouseError} from '../../lib/lh-error.js';
 
 const KEYBOARD_EVENTS = new Set(['keydown', 'keypress', 'keyup']);
 const CLICK_TAP_DRAG_EVENTS = new Set([
@@ -79,7 +75,7 @@ class Responsiveness {
    * one interaction had this duration by returning the first found.
    * @param {ResponsivenessEvent} responsivenessEvent
    * @param {LH.Trace} trace
-   * @return {EventTimingEvent|FallbackTimingEvent}
+   * @return {EventTimingEvent}
    */
   static findInteractionEvent(responsivenessEvent, {traceEvents}) {
     const candidates = traceEvents.filter(/** @return {evt is EventTimingEvent} */ evt => {
@@ -87,15 +83,15 @@ class Responsiveness {
       return evt.name === 'EventTiming' && evt.ph !== 'e';
     });
 
-    // If trace is from < m103, the timestamps cannot be trusted, so we craft a fallback
-    // <m103 traces (bad) had a   args.frame
+    // If trace is from < m103, the timestamps cannot be trusted
+    // <m103 traces (bad) had a   args.frame (we used to provide a fallback trace event, but not
+    //                                        any more)
     // m103+ traces (good) have a args.data.frame (https://crrev.com/c/3632661)
-    // TODO(compat): remove FallbackTiming handling when we don't care about <m103
     if (candidates.length && candidates.every(candidate => !candidate.args.data?.frame)) {
-      return {
-        name: 'FallbackTiming',
-        duration: responsivenessEvent.args.data.maxDuration,
-      };
+      throw new LighthouseError(
+        LighthouseError.errors.UNSUPPORTED_OLD_CHROME,
+        {featureName: 'detailed EventTiming trace events'}
+      );
     }
 
     const {maxDuration, interactionType} = responsivenessEvent.args.data;
@@ -136,7 +132,7 @@ class Responsiveness {
   /**
    * @param {{trace: LH.Trace, settings: LH.Audit.Context['settings']}} data
    * @param {LH.Artifacts.ComputedContext} context
-   * @return {Promise<EventTimingEvent|FallbackTimingEvent|null>}
+   * @return {Promise<EventTimingEvent|null>}
    */
   static async compute_(data, context) {
     const {settings, trace} = data;
diff --git a/core/gather/gatherers/trace-elements.js b/core/gather/gatherers/trace-elements.js
index 487d5ae85c90..6a939d30aadb 100644
--- a/core/gather/gatherers/trace-elements.js
+++ b/core/gather/gatherers/trace-elements.js
@@ -155,7 +155,7 @@ class TraceElements extends BaseGatherer {
     const {settings} = context;
     try {
       const responsivenessEvent = await Responsiveness.request({trace, settings}, context);
-      if (!responsivenessEvent || responsivenessEvent.name === 'FallbackTiming') return;
+      if (!responsivenessEvent) return;
       return {nodeId: responsivenessEvent.args.data.nodeId};
     } catch {
       // Don't let responsiveness errors sink the rest of the gatherer.
diff --git a/core/test/audits/metrics/interaction-to-next-paint-test.js b/core/test/audits/metrics/interaction-to-next-paint-test.js
index 2a301bfaf5fe..54bc94f7b208 100644
--- a/core/test/audits/metrics/interaction-to-next-paint-test.js
+++ b/core/test/audits/metrics/interaction-to-next-paint-test.js
@@ -38,7 +38,7 @@ describe('Interaction to Next Paint', () => {
     });
   });
 
-  it('falls back Responsiveness timing if no m103 EventTiming events', async () => {
+  it('throw error if no m103 EventTiming events', async () => {
     const {artifacts, context} = getTestData();
     const clonedTrace = JSON.parse(JSON.stringify(artifacts.traces.defaultPass));
     for (let i = 0; i < clonedTrace.traceEvents.length; i++) {
@@ -47,15 +47,8 @@ describe('Interaction to Next Paint', () => {
     }
     artifacts.traces.defaultPass = clonedTrace;
 
-    const result = await InteractionToNextPaint.audit(artifacts, context);
-    // Conveniently, the matching responsiveness event has slightly different
-    // duration than the matching interaction event so can be tested against.
-    expect(result).toEqual({
-      score: 0.67,
-      numericValue: 364,
-      numericUnit: 'millisecond',
-      displayValue: expect.toBeDisplayString('360 ms'),
-    });
+    const promise = InteractionToNextPaint.audit(artifacts, context);
+    await expect(promise).rejects.toThrow('UNSUPPORTED_OLD_CHROME');
   });
 
   it('is not applicable if using simulated throttling', async () => {
diff --git a/core/test/computed/metrics/responsiveness-test.js b/core/test/computed/metrics/responsiveness-test.js
index 661bd74e205f..755c0abc21c3 100644
--- a/core/test/computed/metrics/responsiveness-test.js
+++ b/core/test/computed/metrics/responsiveness-test.js
@@ -237,28 +237,6 @@ describe('Metric: Responsiveness', () => {
       .rejects.toThrow(`unexpected responsiveness interactionType 'brainWave'`);
   });
 
-  it('returns a fallback timing event if provided with the old trace event format', async () => {
-    const interactionEvents = [{
-      ts: 500,
-      maxDuration: 200,
-    }];
-    const trace = makeTrace(interactionEvents);
-    for (const event of trace.traceEvents) {
-      if (event.name !== 'EventTiming') continue;
-      event.args.data = {};
-    }
-
-    const metricInputData = {
-      trace,
-      settings: {throttlingMethod: 'provided'},
-    };
-    const event = await Responsiveness.request(metricInputData, {computedCache: new Map()});
-    expect(event).toEqual({
-      name: 'FallbackTiming',
-      duration: 200,
-    });
-  });
-
   it('only finds interaction events from the same frame as the responsiveness event', async () => {
     const maxDuration = 200;
     const interactionEvents = [{