I spun up a docker container instance and updated to the 1.41.8.9914-1d735f17b experimental release (the latest as of today; 1st July) and for my Pixel 8 Pro there is some improvement when compared to my non-docker Synology server (running latest Public Version 1.41.8.9834).
Some shows when played from the experimental docker server now report “Direct Play was attempted but failed, fallen back to transcoding”, where they just outright fail, as before, when attempted from the native Synology instance.
However it’s not all shows that do this, some still outright fail, as before.
Note: I’ve only had 15mins to do some quick tests; nothing exhaustive. And I’m also still using the older, pre-new UI, Android client version 10.26.0.2578