I believe this issue may be related to the bug where you're unable to open marketplace and skin editor (the playfab mismatch bug which I am also experiencing) as both issue started to occur at similar times.
Yes I do restart the world and there aren't any issues for a while but my account disconnects again. It sometimes happens when I launch Minecraft and join a world.
No I have a stable connection. I have also tried restarting my router and turning my WiFi on and off.