Safari 15.4 finally fixed?

It is believed that Apple finally fixed their permessage-deflate ("WebSocket compression") in Safari 15.4. This release will disable permessage-deflate for broken versions of Safari (15.0 - 15.3), but not for 15.4 and forwards. If you experience issues with Safari 15.4 and compression, report it and we can mark 15.4 as broken as well. Apple is not a transparent company and we cannot know what black magic they are up to and their releases do not explain anything.

Think different, think Apple. And now punch yourself in the face. Mmm, nosebleed.