Native HLS/CMAF streaming (abr switching) is broken for both live and vod playback with mixed frame rates

When playing back a HLS/CMAF live or vod stream natively in Safari on macOS I have noticed that the ABR switching does not work if you have for example otherwise 25 fps and 50 fps in the same ABR ladder which is very common.

The issue is that you will get the lower abr stream playback but it will never step up and play the highest abr stream. Removing the 25 fps abr streams then it works and the highest bitrate plays fine.

To me this seems to be a pure bug in Safari. Using the same stream in QuickTime player then it also works fine with having both 25 and 50 fps mixed.

When did this stop working (if it ever has worked) in Safari and is this actually a bug or by design from Apple media playback team?