The "" plugin does not exist.

It seems like the search_api.settings:default_tracker config key is not properly set? Normally, it should have been set to default on installation.
Maybe try reinstalling the module and see if that helps? Otherwise, please tell me the output of \Drupal::config('search_api.settings')->get('default_tracker'); (or look up that config key some other way).

Drunken Monkey, thanks.

You keyed in on something else wacky going on with this site. We've been having issues with things not being installed via config.

lando drush php \Drupal::config('search_api.settings')->get('default_tracker');
zsh: no matches found: Drupal::config(search_api.settings)-

In multiple scenarios we've had to manually copy conifg out of modules in to the site config, to get it recognized.

I'm going to try and manually import the config, and see what happens, will report back.

Confirmed, something is very much up with this install of Drupal.

I manually copied the "search_api.settings.yml" file from search_api/config in to my site config, drush cim, and things work...

Thank you for that gudience.

This is a fresh 10.3.6 install, so I'm going to go look for issues around config not importing on module install...

Marking closed.

Thank you.