The log looks like the device is continually trying to realign audio/video. That's either something from the Jellyfin server or perhaps the network, but my guess is this is about CPU load. It's not clear if you are running Jellyfin on the same RPi? (the Docker add-on is there but we don't list its containers anywhere) but I do notice that 1080p media is being played at (and thus scaled to) 4K.
Implement the whitelist and recommendations here: https://wiki.libreelec.tv/configuration/4k-hdr. This will result in a 1080p home screen and 1080p media playing at 1080p instead of being CPU scaled to 4K. This might not be cause, but as most skins are 720p or at most 1080p native GUI performance will be improved anyway, and it's good to rule this out.