Hi,
I have this issue for few releases ago.
it is not related to the vendor folder/packages.
When I change a method name, the old method name is always in the class definition.
There is like a cache and it is not up to date after each changes so I don't have any error about the method calls.
When I restart VSCode, I get errors because the old method name does not exist in the class definition anymore.
These errors are expected, after to update a method name, we must update all calls.

When I click on F12, the target is:

The method _setData() does not exist anymore.
FYI both classes don't have error, they are not in red state.
Thank you for your help.