I had Studio 2019 Community Edition installed, as well ReSharper. Since we use ReSharper for code analysis, we deactivated Studio code analysis by .editorconfig with only 2 lines:
root = true
dotnet_analyzer_diagnostic.severity = none
Everything worked fine (and still does on another PC).
Now I got a new PC, installed Win 10 from scratch, as well Studio and ReSharper. Now Visual Studio always does code analysis and comments/suggests several issues. Even if I reconfigure issues severity to None, I do not get any changes to my .editorconfig, but still analysing the code.
How can I get rid of Studio code analysis?
This is not a direct answer to your question, but take a look at this article. It describes a way to disable Roslyn-based Visual Studio features through the project properties used by Visual Studio design-time builds. This approach significantly improves memory usage on large solutions.