It depends really which compiler you are testing and whether the version you are testing has just been released or has been around for some time. If the compiler is for a niche language, then it's possible to find bugs. If the compiler has been released, it's even possible to be the first person to note the bug. But the bigger the language, the more has passed, the less likely this is.
This is definitely a big factor. I've found one compiler bug, but it was in a feature that had been added all of two months earlier (optional chaining in Typescript 3.7).
