A quick search showed me that there seem to be lots of issues with the achievement system, in particular people not getting the achievements that they earned. For me it's the other way around: I got 3 major achievements (completing endless mode with >50,000 and >100,000 points, finishing the conquest mode on any difficulty) without actually earning them, just after starting the game for the first time after reinstalling it.

I had last played the game a few years ago and only for about an hour, so I definitely didn't complete any game mode. Also, the date for the achievements is May 30 of 2024, when I didn't even have the game installed. My guess is that that is the date of some update that caused this bug.