corrosion protection wax? on top of hybrid board

[coppercone2]

I was cleaning out some stuff and I disrupted some kind of thin coating on top of a hybrid. It looks like the traces are covered with some kind of stuff (like a solder resist) but then to take it a step further someone put a thin coat of some kind of weak substance that was peeled off by the ultrasonic cleaner.

I want to replace it. what remains of it is a yellowish color. I thought since the bath was 65C, that it may have been some kind of wax. But I am not sure. It is a RF board, paralyene came to mind but I expect it is more durable. I thought maybe someone sprayed wax on it, because it did not flake off, it just kinda.. bunched up, so I noticed ripples, when I rubbed it with my finger it came off, and it feels soft, waxy, rubbery, etc. I think the heat did it. It's very thin, looks better without it to be honest, but I wanted to bring it back.