AV1/VP9 quality options disappear on playback start — CDN restriction error

[drsnt]

App Version

4.3 (12)

Device

iPhone 15 Pro

OS Version

iOS 26.5

Bug Description

AV1 and VP9 quality options appear briefly in the quality picker
while the video is loading, but disappear as soon as playback starts.
If you tap an AV1 option quickly before it disappears, the app shows:

"Quality unavailable (CDN restriction)"

The player then falls back to HLS with a maximum of 960p H.264.

Steps to Reproduce

1. Open any 4K video (e.g. MKBHD, Mrwhosetheboss)
2. Immediately open the quality picker while the video is still loading
3. AV1/VP9/4K options are visible
4. Video starts playing — options disappear, only H.264 options remain
5. If you tap AV1 before it disappears: "Quality unavailable (CDN restriction)"

Expected Behaviour

AV1/VP9 streams up to 4K should remain available and playable.
The A17 Pro has full hardware AV1 decoding support.

Actual Behaviour

Screenshots

No response

Additional Context

No response

[milika]

Update for v4.5: iOS now uses a new default playback engine that embeds YouTube's own player directly. Video quality/ABR is now controlled entirely by YouTube — the app no longer extracts raw streams or exposes a manual quality/"max resolution" picker on iOS, so the CDN-restriction and audio-mute issues from the old pipeline shouldn't occur anymore.

The trade-off: forcing a specific resolution (1440p/4K) isn't something we can offer on iOS anymore — that's now entirely up to YouTube's player. Wanted to explain the change since it directly affects this request.