<PackageReference Include="Microsoft.Identity.Client" Version="4.84.1" />

Microsoft.Identity.Client.Internal.ClientCredential.CredentialTransportProtocol

Determines how the client authenticates when acquiring tokens. Replaces the confusing pair of boolean flags previously used to signal mTLS vs. regular flows.
namespace Microsoft.Identity.Client.Internal.ClientCredential { internal enum CredentialTransportProtocol { OAuth, Mtls } }