All games like this have massive daily player drop offs a few months after release.
To be honest despite the publicity, most players don’t actually give a shit. Most players don’t read gaming news. And many players don’t care, either because they already have a PSN account, or they just don’t care about making another account to play the game.
I wouldn’t be surprised if over half the players had never even heard of the PSN controversy at all. The SteamDB player chart actually indicates when those shenanigans were compared to player numbers, and the daily player numbers had already been declining at that same pace for a month up to that point and continued at about the same rate after.
After Initial Success, Helldiver’s 2 Has Lost 90% Of Its Players With No Signs Of Recovery (www.forbes.com)