Basically you'll have to log into your modem online by scanning the qr for modem management or typing in the ip into your browser for your modem settings. Log in then head over to device management click your ps5 and select ip type reserved hit save then go to advanced settings in your modem and to port forwarding delete any rule with 3074 and then creat a new rule title it bo2 ps5 use udp port in and port out will be 3074 then select your ps5 from the drop down or type in your ps5 ip address press save and restart your ps5. Your nat will now be open.
This happens because another console pc or gaming device has port 3074 as priority and your ps5 cant access it doing this makes your ps5 have priority. Xbox likes to take this port and it can run fine with a moderate nat type once you do this.