I have a problem with downloading nugets with this error.
Unable to load the service index for source https://api.nuget.org/v3/index.json.
An error occurred while sending the request
Error: TrustFailure (Authentication failed, see inner exception.)
Authentication failed, see inner exception.
Ssl error:1000007d:SSL routines:OPENSSL_internal:CERTIFICATE_VERIFY_FAILED
at D:\j\workspace\build-package-win-mono\2020-02\external\boringssl\ssl\handshake_client.c:1132
Mh, I think the error is somehow related to Mono being installed on your machine and nuget using boringssl that comes with Mono. Maybe try unistalling / removing Mono?