I have several fetishes. My main one is a medfet: the patient needing to wear a mask to protect her medically. But I have plenty of others in varying degrees: cable knit tights, mary janes, certain kinds of sleepwear. Masks can be combined with any of these.
My very first medical fetish was actually seeing a girl be given the "black beauty" anesthesia mask. Over the years, that has waned, but never gone. Same with every single other fetish I have. You go through phases of oversaturation with a particular fetish, and then burn out.
But then, give yourself time and it might come back. I was just watching a girl on YouTube have a feeding tube (?
GJ?) replaced. It was done in Radiology, and she was laying down with a mask being firmly held on her face the whole time to give her anesthetic. It was a clear mask---somewhat big on her face but not too big--- with clear tubing, as black beauties seem rare anymore. It was a turn on. She was just relaxed, laying down in her pajamas, mask being pressed to her face, breathing visibly.
I've never felt in danger of losing my fetishes, although I do admit hoping I'm right, sometimes. Just gotta recognize the burnout, like when you've played a song on Spotify too much consecutively. You just move on from that song to another one you've liked for ten years, but haven't listened to in 6 months.
Or in my case, looking at pics of a lung transplant patient in her 3M respirator---being replaced by watching another girl get anesthesia through another kind of mask, something I liked a lot way back in the day. Apparently, I still do, if the girl (patient) is right.