The game's player count has doubled which unfortunately means the CPU is going to be the bottleneck in most systems now. I'm a game dev. Hear me out.
BF3 and BF4 featured 64-player support. However, BF3 on X360 and PS3 couldn't handle the doubled player count of 64. Now, 2042 supports 128-player counts. Xbox One, Xbox One X, PS4 and PS4 Pro can only run 64-player matches. Only PC, Series X and S, and PS5 can run with 128.
This is simply because of how game code is utilised. It is purely a mathematical calculation that is run on the CPU side. Doubling the player count will quite simply double the CPU cost per frame for synchronising positions. I'm going to guess that position synchronisation logic is the bottleneck out of all CPU tasks with this game given the player count limitations of the past and present platforms. There's isn't a simple fix for this, unfortunately.
FYI, I'm running a 6800 XT which in most cases can net me 144fps. My 3600 however, struggles to achieve 90 in a 128 match. This is not a bug, it's simply how the game is designed.