Since coming back from a loan stint with Tottenham Hotspur last season, Bale has made just three appearances for Los Blancos – the same number of times he has played for Wales in 2021-2022 – because of a troublesome thigh injury.
Despite including two LaLiga titles, four UEFA Champions League medals and a Copa del Rey on an impressive resume with Madrid, the club's fanbase has often made Bale the subject of its ire.
It was put to head coach Ancelotti that he had protected Bale like a father in the past, but the Italian said his achievements at the club should always be remembered.
"I'm not his father, firstly. It may be that Bale's last period was not good, but nobody forgets what Bale has done," he said ahead of Madrid's LaLiga contest with Rayo Vallecano.
"In 2014 he helped us win the [UEFA] Champions League, the Copa del Rey, in 2018 he helped us win the [UEFA] Champions League against Liverpool.
"The fans are not forgetting this. He is not having his best moment, but we have to have faith. When he comes back from the national team, if he deserves to play, he will play."
Bale is set to link up with Wales despite not being available against Vallecano this weekend.
Ancelotti confirmed Madrid cannot prevent Bale from playing during the international break as he has recovered from injury and has been training this week.
"He has trained well, but he is not called up. He goes to Wales and the national team will evaluate whether he can play or not. It will depend on how the player feels. They will decide there," he added.
"The important thing is that Bale is fine, but after two months out it is important what the player feels.
"If the national team calls him, we have to send him. We explain how the situation is and then Wales have a week to assess the situation. I think Wales are not going to take a risk."
Another player who has not always found favour with the fans is Eden Hazard, who has been frustrated in his pursuit of regular football this term with Vinicius Jr preferred on the left of attack.
Ancelotti is planning to give Hazard some game time this weekend, and the coach applauded the Belgium star's professionalism.
"Hazard is not happy, because he has quality, he is professional and he is training well. He deserves to have minutes and he will have minutes, by the way," the Italian said.
"If he continues to have faith, he will have minutes. If he will have them on Saturday, I don't know. The important thing is that he is plugged in.
"I am sorry because Hazard is very professional. Whether he will play from the beginning, I have to think about it."