I was working for mid-level corp writing a C# Windows program that would be used by a few hundred people tops.
Even after going through the signing process, there were still false positives from some major anti-virus vendors.
I had to submit and resubmit to multiple vendors to get the program off the false-positives. Some smaller vendors still triggered.
Microsoft Defender was one of those that I had trouble with even after the signing.
So if you write software for a smaller audience you are going to get screwed.