Originally posted by scootytheclown:

Steam Client "Validating", watch your Library list on the left and you'll catch it beside the game title. The last new update introduced some weird behaviour. Happens with a lot of games now. I get up to 4 games doing this every time I log in.

Yeah in my particular case, I just wiped out my SSD and installed only 8 games. 2 of them are constantly updating everytime I turn on the PC (noita and valheim).
Something similar happened months ago with some security patches for CSGO, for example, and a couple of fps.