That, my friends, is SmartScreen. A reputation based filter from Microsoft that many modern browsers use. You can get the details here if you want to read about the justification for it, or how it can supposedly help... In the end it prevents 'unknown' programs from running without a prompt to the user first... That's kind of a good thing, unless you're releasing a new version of your software and signing with a brand new certificate... Right? Well...
You do not need a $1000 EV Code Signing Certificate to get around SmartScreen. You need a computer, Internet Explorer or Edge, and about 10 minutes of time.
All you need to do is use IE or Edge and download the untrusted file. When the SmartScreen warning comes up click “More” or “More Info” and “Run Anyway”. Do that about 10-15 times and in an hour or so after that the messages go away. Make sure you're downloading your signed file though as this only really works if the downloaded file is signed. Once one of your signed files gains reputation any other file you sign will share in that reputation.
See? Not that bad at all, is it!