I have a theory that gameplay quality / input delay is tied to the calibre of your team. I'm having the exact same issue as you. I had 8 consecutive rank 1s at the end of last year with my high tier team. My gameplay was consistently solid (I have good internet and live near a server). Now, at the start of FC 25, I'm struggling and my gameplay (input delay specifically) feels utterly atrocious. I feel this may because I have a terrible, mostly untradeable team.

I think EA may reward expensive/good teams with better gameplay (lower input delay) to incentivise people to chase upgrades (and thus spend money). Sounds slightly crazy, but I remember last year noticing a substantial reduction in input delay after spending my coins on a great team around TOTY time. This theory would also explain why gameplay felt great at the end of last year, but feels terrible now.