There are a couple failures mentioned in this tweet:
https://twitter.com/simevidas/status/1269265131701260293

• issue with mix-blend-mode.
• issue with :visited not being taken into account.

Here’s a simple demo for testing purposes: https://jsbin.com/piloqon/edit?html,css,output

(In reply to Šime Vidas from comment #1)

Here’s a simple demo for testing purposes: https://jsbin.com/piloqon/edit?html,css,output

Thanks!

I have found another issue: When a link has low contrast but good contrast on hover, if you select it with the accessibility picker, it will say that it has good contrast because it uses the style from the :hover state.

Test page: https://output.jsbin.com/katozop/quiet

See the screenshot in the attachment.