The bubbles on this demo should have color, and do not:
Mentioned on https://css-tricks.com/using-custom-properties-to-wrangle-variations-in-keyframe-animations/
I am able to reproduce this bug in Safari Technology Preview 152 on macOS 12.5.1 using CodePen from Comment 0 and it does not update color on circles while Chrome Canary 107 and Firefox Nightly 106 show color matching with text when you hover or move mouse on the CodePen. In case of Safari, the color remain just grey for bubbles.
Just wanted to share updated testing results. Thanks!
The issue is the we don't invalidate keyframes when a variable value changes so fail to reflect changes correctly. To implement this we need to track if the keyframe uses any variables and invalidate it on variable mutation (preferably only when a variable that is actually used changes). There is somewhat similar mechanism already for container units (KeyframeList::usesContainerUnits() etc).
We did some work recently (see bug 248145) to improve support of CSS variables with animations but this bug persists.
I was wrong, this is fixed in ToT, marking as a dupe.
*** This bug has been marked as a duplicate of bug 248145 ***