You can already guess the third sentence: the servers have been a disaster at launch, with players forced to queue for long periods just to play alone, if they can manage to play at all. It currently sits "Mostly Negative" reviews on Steam - that's 31% positive after almost 19,000 reviews.
"Online only was a huge mistake," says one review. "Imagine waiting for an hour and ten minutes and still not being able to get into a private game," says the one underneath. "this game makes me feel the developers made this game just so they could pull off the biggest heist of all time. robbing us of an offline mode," says another. There are hundreds more like this.
The official Payday X (formerly Twitter) account has been tracking the issues, noting "slow matchmaking" on September 21st, and an outright "matchmaking outage" yesterday on September 22nd. As of twelve hours ago, the account posted that they're "seeing players being able to create lobbies again," but that there "still might have a few issues" that they're working on. Throughout it all, the account has been getting roasted by players who can't play, or who simply want an offline mode.
Alice B wrote in her Payday 3 review that it had some fun levels and fine shooting, but was ultimately letdown by its matchmaking - not because it didn't work, but because it was random, without the controls offered by its predecessor. That sounds like a decent game that would probably be getting decent reviews on Steam right now if it wasn't 'always online'.