https://github.com/web-platform-tests/wpt/commit/f00b5b08edd7f40b32e30e196fc58829934c9b38 exposed a bug in the implementation with transform individual properties (scale / translate / rotate) where WebKit doesn't support calc().
<rdar://problem/118727471>
I looked more into detail, and the bug is actually that we don't serialize correctly identity transforms.
Pull request: https://github.com/WebKit/WebKit/pull/20891
Submitted web-platform-tests pull request: https://github.com/web-platform-tests/wpt/pull/43352
Committed 271115@main (5d05c38e6daa): <https://commits.webkit.org/271115@main> Reviewed commits have been landed. Closing PR #20891 and removing active labels.