Visual Studio 2019 has a feature where it inserts lines showing you "reference counts":
How do i turn them off?
Note that the option Show C# and Visual Basic references
is disabled and cannot be unchecked.
How do i uncheck it?
The answer remains, when Codelens is enabled, reference count is always shown. The feature has been unchanged largely since introduction and this has always been the case.
I'm not 100% sure about the reasons, but what I remember it has to do with reserving the screen realestate in case new indicators are activated later on due to context to prevent the code you're working on from jumping around.