It's been happening to me too, though now with the added caveat of my Anti-Virus program popping up every minute or so to tell me it has quarantined a file.
If you got your build of Playscii from here on itch.io, it should be safe to run. It looks like Bitdefender's submission/appeals process for false positives is limited to "enterprise" customers, so I can't really do anything about the detection from my end. Try telling Bitdefender to add an exception for it: https://www.bitdefender.com/consumer/support/answer/13427/