I'm running the latest nightly build (LibreELEC-Generic.x86_64-12.0-nightly-20230917) and when I try to install the Youtube plugin from the official Kodi repository I get an error that the "InputStream Adaptive" dependency cannot be installed. Note that this same PC previously ran "Kodi from Debian" and that same plugin was installed successfully.
Anyway, apologies if this is a known problem, but I couldn't find any information about it on this forum. If the problem is new I can help to debug it by posting logs, etc.