There’s been a huge drop of players because classic is actually a pretty terrible game as evident by all the posts here demanding changes.
Before you says “mega servers” let me remind you that while originally there was no mega server there was also no layers or hyper spawns so full servers had the same competition for mobs back then as they do on mega servers.
What you’re realizing is you are not enjoying classic like you remembered and that’s totally normal because people tend to forget the bad and only remember the good parts