Thanks for the report.

The specificity of .editor-styles-wrapper a:not([class^=components-]):not([class^=editor-]):not([class^=block-]):not([aria-owns]):not([id^=mceu_]) is 0,6,1.

I couldn't find such a selector in the Gutenberg project. Also, for example, if I define a link color in a group block, the CSS selector will be as follows (Tested on WP6.4.3):

.editor-styles-wrapper .wp-elements-0 a

Is there a way to reproduce that selector?

Thanks for your feedback. That selector is copied from the developer tools inspector, from any link in the editor.

Maybe it's due to another library? I found the issue below.

m-e-h/postcss-editor-styles#2

Thanks for taking the time to submit this issue @markhowellsmead 👍

I'd like to second @t-hamano's comments here.

There are no references to any of the a:not clauses from the reported selector within Gutenberg or WordPress core. It stems from the postcss-editor-style plugin here.

On the Gutenberg and WP Core side of things, link colors are applied in the following manner:

Within the editor, the selector used to apply link colors is a:where(:not(.wp-element-button)). It gets applied to specific blocks by scoping that selector with a single class generated for that block instance e.g. .wp-elements-0. This also matches the selector and approach used on the frontend.

As this is an issue with a plugin rather than Gutenberg specifically, I'll close this GitHub issue.