Not sure.
I know of at least one person that found the problem was with their own router that was causing lag/latency spikes while playing.
I get them occasionally, but I know exactly why those happen. (trees that slightly obstruct my Starlink)
But if I use my backup DSL line, no issues at all. I even enabled Crossplay again, and see more players in game, and even then it plays fine.
Time to start running down the check list. You can use this older thread with a lot of compiled network troubleshooting tips:
-For everyone having connection issues of various types: UPDATE 8-7-23