I'm not sure what's going on but for some odd reason steam just started auto-unlocking achievements for some of my games. Anyone else came across this strange issue?

First time I noticed it was two or three days ago when I started the client and all of a sudden I got 4 achievements for American Truck Simulator. At first, I didn't think this was much of an issue as there was an update rolled out for the game at the same time and it looked like my achievement progression was simply updated, so I left it at that.

Second time this happened was earlier today when I started Lust Goddess and the client just dropped two super-rare achievements out of the blue I could have never obtained in a lifetime! Since this is a far more serious issue then the one mentioned above, I contacted their support right away to ask for a reset if possible.

The thing that freaks me out the most about this is how my completion rates are being totally messed up. I don't want my account to be flagged for violating some ToS, or come under the suspicion of using hacks - especially since all top-league achievements in LG are paywalled!