Which means what exactly? Some kind of ghost issue?
Low being a relative term, it is hard to make a great deal more of it than your mechanic thinks it is suboptimal.
I certainly don’t think there is anything paranormal about your symptoms.
If your mechanic said when we saw that low compression, we shot some oil into the cylinder and it popped up, I would say your rings may be shot, but in the absence of more detail, I can only say it likely is less than say 100?