What do you mean by "being flagged"? My understanding is that permission issues aren't a result of some "malicious software" detection heuristic, just a set of rules that applications have to follow to be able to do things like access different parts of the file system. Not knowing anything about how those rules might have changed for Win11, I could be wrong but that's my guess as to why you can't get a file listing for certain directories on your system from within Playscii.
You probably understand that better than I would, yeah. I don't know much about permission architecture. Most of my experience in programming is in the aforementioned engine which handles this part for me, as well as some early-life python doodling. Do let me know if you figure this out, but I myself don't have the experience required to help fix the bug; I was just affected by it.