Fifa has had this feature of randomly weakening one of the teams in online games, perhaps some kind of AI for balancing the game play or make players buy more carts/consumables to survive.
This feature sucks and ruins the joy of a fair competition , it's not important if my team is being weakened or my opponent's.
Players become slow and stand in wrong positions, even with setting all the strategies to attack, players do not participate in attacking, best players with high attributes lose simple passes or shots through the whole game and the goal keeper does not care about saving anything !
One positive change in fifa 21 is putting limits for replays and celebration, which could be so annoying in previous versions, if the opponent used them as a tactic for killing the spirit of the game in his/ her own favor.