There are multiple kinds of search filters but in "Project Files" dependencies are also included:

But event having selected only Project Files the dependencies/libraries are been read by IntelliJ like project code for some reason, it makes searching on the code harder.
Versions
- Flutter plugin:
51.0.3
- Intellij Community:
2020.2
Examples of problematic behavior
1
I try to search with "find in path" (cmd + shift + f) results contains dependencies files:

The only result that belongs to the project is the first one, but I get a big list of files from the project libraries.
2
I try to search a class name (cmd + o) I see library classes and the same thing for another kind of searches.

The only result that belongs to the project is the 4 and the 5, not even the first results belongs to it.