@Eguzky-0 The problem is not really on the client end.
The problem is very very much on server-side. Lots of UI stuff triggers netcode events.
The problem I'm seeing a lot is suggestive of server memory being insufficient, like they're running them on under-provisioned virtual machines. I've seen these exact same kinds of lag issues in another game that predates PSO2. Basically, when you move around the map, you cross through different sectors which are virtual channels, so that only 8-32 people can be in them. This part works well enough, however whatever the underlying netcode is doing, is resulting 5sec to 2-minute long lag spikes (suggestive of swap thrashing), so this results in things like hitting a boss for a minute, while everything else is not moving, and then suddenly you see the flying text a few dozen times and it falls over dead.
The same thing is also affecting the display of resource nodes, where, even if you have a quest to find that item, the quest marker is not showing up. The game that predates PSO2 also had this kind of problem. Every time something moves, the client has to interpolate the positions of everything.
So when either the server has issues, or the data center has issues (eg Ship 2 is super laggy, but Ship 3 wasn't nearly as bad) suddenly everything connected to that server becomes congested.
Now I assume this will eventually get fixed, but for the most part, no MMORPG has ever had a flawless launch.
Here's a potential "bug", and I don't know if others have observed this, but on Ship 3, which was an imported character, it took me around 12 hours to get from level 1 to level 10. But on Ship 2, which was a 2 character, PSO2NG only, I got there in only 6 hours. Despite ship 2 being horrifically laggier.
This makes me wonder if the server is mis-calculating positions and rewarding experience just for being anywhere near mobs even if not fighting them. So a more congested server might be over-distributing experience, money and such.