Can't add reference of ClassLibrary: Shared into ClassLibrary:Application

[faisalshafisit]

Application and Domain Class Libraries are in .Net Standard 2.1
Whereas
Identity, Persistance and Shared Class Libraries are in .Net Core 3.1

Therefore I'm unable to add project reference of shared into Application ClassLibrary.

[KanupriyaGoel]

I am not even able to add a new class library project. It gives compilation error. Were you able to resolve this issue?