I had issues when requiring tox and flake8 because of this pin.
Shortened error from pip-compile-multi:

Could not find a version that matches importlib-metadata<4.3,>=0.12,>=0.22,>=1.1.0,>=4.8.3 (from tox==3.25.1->-r requirements/local.in (line 3))
Tried: ............
There are incompatible versions in the resolved dependencies:
  .......
  importlib-metadata<4.3,>=1.1.0 (from flake8==5.0.4->-r requirements/test.in (line 6))
  importlib-metadata>=4.8.3 (from virtualenv==20.16.3->tox==3.25.1->-r requirements/local.in (line 3))

In my case, pinning virtualenv==20.16.2 ; python_version < '3.7' avoids the problem, but my project will be locked on virtualenv version 20.16.2 until this can be resolved.

Is there a reason for importlib-metadata to be pinned as >=4.8.3? I'm not super familiar with the library, and the problems around it, but unfortunately looks this isn't the only issue out there when projects pin it.

Is there a reason for importlib-metadata to be pinned as >=4.8.3?

That's the only version we actually test with in our CI and is the only version I'm comfortable saying it's supported. I recommend reaching out to other projects that upper pin to remove.