What did you expect? They have not played well in any game since the beginning of the league. It would be absurd to expect them to give high performance in the league where they remained untargeted after this time. There was at least one goal in European matches. There is no difference between finishing 5th and 15th in the league, except for a very small amount of prize money.
You can't motivate players that way. Everyone is already on vacation mentally. Even if the league is over, they are playing in the mood to go. The plans for the next season are being made in the head.
Other than Fenerbahce game, they only have Basaksehir game left for Istanbul teams. Others are relatively unimportant Anatolian club games.