This has been reported in the German forums as well: mAirList v7.3 public beta: Fehlersuche - #37 by Calypso
Most likely a false positive. Defender is notorious for that. I checked the mAirList.exe on virustotal.com, and all scanners say it’s clean, except Microsoft.
Interestingly, on my own Windows 10 VM I use for development, supposedly with the latest Defender updates as well, none of the files were flagged.
I have rebuilt and re-uploaded all versions that I released yesterday, not it seems to be OK. Please download (make sure to clear browser cache!) and try again.