Ok, I solved it; it was one of the the antivirus tools, the Advanced Thread Defender (ATD) from Bitdefender.
Usually when something is flagged, I get an alert with a red dot under a bell symbol, but I didn't get any. So to be sure, I ran the executable disabling each of the antivirus features at time and the culprit was the ATD, so putting it under exceptions fixed it.
I was kinda worried why the ATD didn't show me any event, so I copied the game to my laptop, which has a clean copy of W11. ...and it was blocked again (same memory error) without any warning. This time, it was silently flagged by Microsoft defender/UAC.
I dunno why this game is so problematic...