Polyp in mouth

[Rescue Momma]

One of my Arlington TX chins has a polyp on the roof of his mouth.
Have had him to two different exotic vets and they have no idea what/why he has it.
Last visit he said at some point it would grow to large and he would not survive.
Has anyone else ever seen this?
Tonight he is making noise when he breathes. Sounds wet like congestion.
Two vets don't know so thought I would ask the experts.:help:

 

[tunes]

I have not experienced this, however, what the vet says makes sense. So why would they not remove it? If it is going to cause issues with breathing and eating and so on, have they not suggested removing it at all?