[omajid]

Microsoft publishes a patent promise here, though: https://github.com/dotnet/runtime/blob/main/PATENTS.TXT

[cardanome]

"We promise not to sue you" is much weaker than a proper patent-grant.

That promise seems only to apply if you use the .NET runtime. If you used a forked project, it might not apply.

See also: https://endsoftwarepatents.org/2014/11/ms-net/