It was time to bite the bullet and upgrade this site to Drupal 10, which went pretty smoothly, but of course, never start this sort of process without a backup.
Drupal has made huge advances with upgradability since Drupal 7. Going from Drupal 8 to Drupal 9 and now to Drupal 10 has been a progressively smoother process.
In the case of this site, it was simply updating composer.json and changing some lines in composer.json like this:
Before:
"drupal/core": "^9.5", "drupal/dynamic_entity_reference": "^1.16", "drupal/linkit": "^6.0", After:
"drupal/core": "^10.0", "drupal/dynamic_entity_reference": "^3.0", "drupal/linkit": "^6.1",
Then run composer update and test locally with a backup. Always test locally with a backup first.
Everything tested out ok, so next was a push to GitHub, let the GitHub action build the docker container, and then deploy and run database updates.
Total downtime, less than a minute.