This has been an ongoing issue for awhile now, its not just a Murder Miners thing.
It appears to be an issue with Visual Studio when compiling .NET applications.

I've been scanning the .exe each update, the current version of the Murder Miners .exe is coming up clean on VirusTotal: https://www.virustotal.com/gui/file/85dc80ef3d43e91faf045a28b4b130e9de617be6c7bb450cdd0f6ba5953d41d6/detection
We have contacted Microsoft about it many times and they usually fix it, but as soon as we update the game it starts happening again.
I would encourage you to scan the .exe yourself.

The game has been detected as a multitude of different things over the last few months and other people are getting the same problems with their own projects it seems.
https://developercommunity.visualstudio.com/t/windows-defender-reports-a-trojan-1/1046937
https://www.reddit.com/r/VisualStudio/comments/frmg2b/windows_defender_is_detecting_a_virus_when_trying/
https://community.spiceworks.com/topic/2260149-false-or-real-trojan-threath

It may be helpful if you could let us know what the game is being detected as.