My partner and I did experience the issue when we would get kicked constantly from multiplayer sessions (ticket lodged, one follow-up response, PC has good hardware - 3080ti etc, and good connection - 900Mbps/50Mbps).
Since patch 1.1.2 we have staggeringly low frame rate - though the host suffers not performance issue. We swapped who was hosting and the low frame rate only affects the one joining, not the host.
The game is unplayable for the one joining. Frame rates are like 1 -2 frames per second. No bottle necks observed in Task Manager. Game runs fine for host.