It's really disappointing, especially considering how powerful the console is supposed to be

It doesn't really have that much to do with the power of the PS5 as people with high-end PC's are having the same issues. The problem is the amount of data that is required to play this game even in 1-player. I find it quite odd that this game needs to be always online, even when playing in single-player. This creates the lag and it wont be resolved until the devs figure out a way to improve their network infrastructure to accommodate the millions of people trying to play it all at once.