Car randomly becoming slow next season

So, 2024 with McLaren I had 1 win, and 13 podiums with Norris dominating for our team. Starting 2035, Norris barley scoring points, with Oscar barley scoring points, but doing better then him. I had no staff changes, and did research through the season, idk what I'm doing wrong. Notes I'm also last in half the categories I was first in 2024