My setup is as follows:
ps4 and pc next to each other, 1 keyboard for both of them
when playing ffxiv my keyboard is mainly attached to my ps4 but sometimes i unplug it to do some stuff on my pc

sometimes when i detach or re-attach my keyboard to my ps4 other people won't see me typing in chat and i can't see what other people typed in chat
shortly after this happens (a minute or longer) the game disconnects me with a 90001/90002 error

this has been happening for a long time to me and i think this is what's causing it