A typo, NV12 is listed twice instead of both NV12 and NV21.
Pull request: https://github.com/WebKit/WebKit/pull/1175
Committed r295046 (251141@main): <https://commits.webkit.org/251141@main> Reviewed commits have been landed. Closing PR #1175 and removing active labels.
<rdar://problem/94142379>