Arbitrary Values Not Supported for Special-Character Prefixes (e.g., @) in 3.1

[ITenthusiasm]

What version of Tailwind CSS are you using?

3.1.4

What build tool (or framework if it abstracts the build tool) are you using?

[email protected]

What version of Node.js are you using?

v16.14.0

What browser are you using?

Chrome

What operating system are you using?

MacOS

Reproduction URL

https://play.tailwindcss.com/0B55HN10nd

Describe your issue

Unlike in [email protected], arbitrary values no longer work as of v3.1.x if a special character (e.g., @) is used as a prefix. One can see that the regular class names work just fine, but not the arbitrary content styles. Related to #8601. (I actually just augmented their example for this use case.)