@TiggrToo thank you for your answer! I did install Malwarebytes and it showed no threats detected. Is that clear confirmation that I'm OK, or should I do something else? I really don't know why it showed up, and it stayed like that for couple of minutes, that verifying didn't seem to move. I wonder if it could be related to audio production, which is what I use this computer for, since I saw couple of people mention that library call in their problems:
https://discussions.apple.com/thread/253471601
https://www.reddit.com/r/GarageBand/comments/sb12f7
But the problem is I'm not using neither GarageBand nor Logic Pro, I use Cubase. But still, maybe it's related to some audio-plugins, and not a virus.