Block variation: templateLock not working

[huubl]

Description

Setting the templateLock attribute to contentOnly in a block variation is not working.

Step-by-step reproduction instructions

1. Register the "cover-locked" block variation using the provided code.
2. Insert the "cover-locked" block into a post or page.
3. Save the post or page.
4. Reload the page.

Screenshots, screen recording, code snippet

wp.blocks.registerBlockVariation("core/cover", {
	name: "cover-locked",
	title: "Cover Block Variation Locked",
	description: "When reloading the page, the templateLock 'contentOnly' is lost.",
	category: "media",
	icon: "smiley",
	attributes: {
		templateLock: "contentOnly",
		useFeaturedImage: true,
		dimRatio: 0,
		backgroundType: "image",
		overlayColor: "",
		isUserOverlayColor: true,
		contentPosition: "center center",
		isDark: false,
		className: "is-cover-locked",
		tagName: "div",
		textColor: "white",
		layout: {
			type: "constrained",
			contentSize: ""
		},
	},
	innerBlocks: [
		["core/heading", {level: 1, placeholder: "When reloading the page, the templateLock 'contentOnly' is lost."}],
	],
	example: undefined,
	scope: ["inserter"],
	isDefault: false,
	isActive: ['className'],
});

Environment info

No response

Please confirm that you have searched existing issues in the repo.

• Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

• Yes

[talldan]

Thanks for reporting, I could reproduce it. It looks to be the same kind of issue we had for the group block recently (see - #63837).

There's a block deprecation that causes the attributes to be stripped:

gutenberg/packages/block-library/src/cover/deprecated.js

Lines 401 to 412 in 46f9fe0

	isEligible( attributes ) {
	return (
	attributes.customOverlayColor !== undefined ||
	attributes.overlayColor !== undefined
	);
	},
	migrate( attributes ) {
	return {
	...attributes,
	isUserOverlayColor: true,
	};
	},

The isElligible function is the main issue. customOverlayColor or overlayColor are currently in use and valid block attributes for the cover block, so I don't understand why this implementation checks for them. It causes the deprecation to match against perfectly normal use cases of the block.

The issue was introduced in #54054 (cc @ajlende)

[andrewserong]

I think I have a fix for this over in #65105.