Same here i also suffer from fps drops. I have gaming laptop with rtx 3050ti i5, in the game suddenly fps goes to 5-10 and then go back to normal. It doesn't matter if it's teamfight or not, randomly drops.
I don't know if it is a bug or not but my final rank after the first ranked session was Oracle V and while i'm in ranked games and press ESC i see i'm Phantom 3. I thought it was gonna be visible only after the session.