[4.22.2] Engine rebuilds entirely after adding plugin to Project

I did the following:

  1. Downloaded a 4.22.2 custom source branch (without many changes from release)
  2. Ran Setup.bat and GenerateProjectFiles.bat
  3. Built the engine
  4. Created a new C++ project, which opens fine
  5. Deleted the UnrealEngine\Engine\Intermediate folder to save space
  6. Downloaded a 4.22 plugin from the Marketplace and copied it to my project\Plugins\Marketplace folder

When I open the project, it asks if I want to build the plugin. If I select yes, the entire engine starts rebuilding. If instead I don’t delete the Intermediate folder in step 5, it just builds the plugin, as expected.

Is this normal? I don’t think this happened with my 4.20.3 build (after deleting Intermediate), but I don’t have space for two source builds so I can’t check.