Issue
The .NET for Android build will emit a XA0105 warning if it detects that one of the referenced libraries or projects is using a $(TargetFrameworkVersion) higher than the project being built. Using libraries which are targeting a higher $(TargetFrameworkVersion) can cause unexpected results at runtime, especially when running on older devices.
解决方案
The fix is to increase the $(TargetFrameworkVersion) for your project to be equal to or higher than the referenced library projects.