I remember working on a car and running out if icing, with a little spot left to repair around the jeep embossed logo. All the auto parts store had was the red bondo spot putty, which is lacquer based. Put it on. let it dry, sanded, primed and it bubbled. Sanded it all out, filled again, waited overnight, primed and it bubbled. There are a few things I consider alive. Epoxy flakes falling off plastic and burning into the urethane paint, brand new silicone masking plugs that usually raspberry around holes I plug when they are new, and lacquer. There might be a way to sand the lacquer, then wait like 2 months for it to solidify again, then seal and try to go on top, but I am not going to be the one to try that.
The million dollar question, or maybe 2 bits, is how can you find out if it is a lacquer or not? If it was recently painted, like over the last 20 years, there is a chance its urethane. Is there a test? I am thinking white, you would maybe, just maybe do some kind of a uv light test. Mask an area, then put a blacklight over it for a while, unmask and see if it changed?
Probably doing the usual of overthinking things, but if you could find out it was a polyurethane somehow, you would be saving alot of work. I would expect the poly to hold up well to the uv but the lacquer discolor. Any thoughts?