1. respect the pinned post in this forum on posting an OBS Studio log (link in my .sig)
check the log yourself and see if your audio sampling rates all match... if they aren't, best to adjust (at operating system level, not OBS) to all be the same
2. lots of possibilities, often plug-in related, or under-powered hardware... but not always
A OBS Studio log won't tell anyone how your devices are physically connected, and any Operating System level drivers and audio software, so be sure to include some of those details as well.
Other things that could be happening in your background tasks, for whatever reason, or now causing some sort of contention (CPU overloading, or ??). Driver and Operating System updates can change behavior