Yoast overall score is not updated, always Unknown and gray.

I had this problem as well and yoast_seo_update_8203 should've taken care of that and created a settings file.
Do you have a yoast_seo.settings.yml file with the contents below?

score_rules:
  0: 'Not available'
  8: Good
  1: Bad
  5: Okay

That update was somehow missing.
Now it works for some cases. But not for every content type.
But I don't know yet why some content types have scores and some don't.

The issue suggests this wasn't an issue in the module. I'd need more info to know if there's a bug to be fixed.

I think this has to do with jumping from the 8.1 to the 8.2 version. Is there a recommended way of doing the update?

I have a probably related jumping problem:
drupal updated from 10.4.6 to 10.5.1
upgraded yoast_seo from 1.9.0 to 2.2.0

and suddenly all nodes for every bundle seo are bad or unavailable, no snippets, nothing.
No errors in teh reports.
No javascript errors.

Compare the two screens shots

I have added the yoast_seo.settings.yml as mentioned in comment #2 and got console errors.

Made a patch to address this. Please test this and let me know.

also tried to jump from 1.9.0 to 2.0.0 and 2.1.0 in drupal 10.5.1
Same results als upgrading from 1.9.0 to 2.2.0

And suddenly all nodes for every bundle seo are bad or unavailable
no snippets, nothing.
No errors in the reports.
No javascript errors.

I have the same bug as #6 after upgrade from 2.1.0 to 2.2.0. Rollback to 2.1.0 restores functionality.