The compositing coordinator is passed as the client of the root layer, which doesn't have backing store and it's handled manually, so every time it changes we are already scheduling a layer flush.
Pull request: https://github.com/WebKit/WebKit/pull/19224
Committed 269509@main (5603d6693703): <https://commits.webkit.org/269509@main> Reviewed commits have been landed. Closing PR #19224 and removing active labels.