The competition at Real Madrid is so tight that Gareth Bale continues to be on the bench because Zidane knows who to play in his first team, with this move to Tottenham of course reminiscing about the past before whether it will repeat itself with Gareth Bale's previous performances? Now that Bale is 31 years old here is old in my opinion so his appearance will decline a little with these conditions, if Mourinho continues to try to rely on Bale's daru wing with these adaptations it can restore his appearance.
Gareth Bale has loss zidane trust in Real Madrid in my opinion not about the priority of the main squad but he has personal problems with Zidane that's why he played less and more often on the bench,
in His current age 31 years does not give a big picture that his performance will decline or worsen, do you see zlatan, at the age of 39 he remains a deadly predator in front of the opponent's goalpost.
I believe if he continues to be played and his career that has been dimmed all this time, his performance will return to the same as when he was with Spurs.