https://compat.spec.whatwg.org/#css-gradients-webkit-radial-gradient From code inspection and a failing WPT test, it is clear that the parsing for -webkit-radial-gradient accidentally is treating commas separating some of the items as optional; they should be mandatory.
<rdar://problem/102111231>
Pull request: https://github.com/WebKit/WebKit/pull/6270
Committed 256468@main (a62f77706c4f): <https://commits.webkit.org/256468@main> Reviewed commits have been landed. Closing PR #6270 and removing active labels.