I've been using LibreElec / Kodi on a Raspberry Pi 4 for quite a while now, and of course I am looking forward to the upcoming 10.0 release. Today I tried 10.0 Beta 3, using a fresh SD card as recommended in the release notes. Everything worked nicely, the user interface is rendered smoothly and system information shows that the CPU load is minimal, looks even better than with 9.2.x.
However there's a problem with playback of H264 video. I've also tried mpeg4, that seems to work fine. But any H264 encoded movie, or stream (I tried Vimeo), comes out totally garbled. In some films some i-frames seem to render okay, but most of the time the picture is so garbled that it's almost inconceivable. Here's an example picture, most of the time it looks even worse:
The Raspberry Pi is attached via HDMI to a projector with 1080p resolution. Needless to say that the same movies and streams play back nicely using the 9.2.x release.
I've attached a debug log and the kernel output, let me know if any other details are needed: