drupal/core-dev install fails if drush/drush already installed

This happens to me also on core 8.9.20

It is not a big problem, as I only used Drupal 8 to run Upgrade Status module, and it is solved by removing drush, installing dev-core and installing drush back.
But it can be reproduced, so "cannot reproduce" is not a correct status here, also the user who put "cannot reproduce" status used Drupal 10 and the issue is reported on Drupal 8.

This is still happening in the latest Drupal 9.5 version (see installing drush before drupal/core-dev breaks the project #5372), so setting status back to "Active".

In the drush issue linked in #15 greg-1-anderson recommends, that

Recommended Strategy: Composer works best if you install projects with highly specific dependencies, like drupal/core-dev before projects like drush/drush that have loose dependencies that allow it to work in a lot of different environments.

So, it appears that this is a documentation issue for Drupal. And Drupal documentation → has been updated.

What else is left to do here?

I've just run into this when working on Drupal 9 - removing drush (composer remove drush/drush), requiring core-dev then re-adding drush works fine & gets around the issue. I'm not sure there's anything core needs to do here, though perhaps the documentation could suggest to remove & re-add drush.

I've just tried this without specifying a Drupal version for the recommended project (so currently uses D10), and was able to install drush before core-dev without any issues, so perhaps this is specifically an issue with D8/D9.

Based on #17 I think this can be closed, given that Drupal 9 is no longer supported and no one has reported issues with Drupal 10.