By unusual I meant for example stripping the CRT, or it may indeed have to do with not having main
; anything which is not that commonly done. But these are all guesses and don't really mean anything, just something which may contribute to some AI false labeling it as malware.
Also, your load config table seems to be invalid which may be "suspicious", but I don't know why that would be of the top of my head since you seem to be compiling it quite normally. Some info on it from the MSDN page:
Maybe also enabling /guard:cf
would somehow lend more legitimacy (both are currently disabled).
Other than that, I'm not sure you can do much which isn't playing the algorithm (e.g. dynamically loading some of the imports to trip machine learning models up). Packing it with something like UPX might be a hack which works, but better solutions usually unpack these so it might not have any impact, but who knows.
For personal use, you can add "Exclusions" in Windows Defender, folders which won't be scanned for malware. It should leave everything in exclusion folders alone.