Extra tables in the database of a long-running OJS instance

I have an OJS instance that started out as OJS 2.1. When I compare its database schema to a refresh install of OJS 3.4.0.6 with the same plugins active, I have a lot of extra tables. I presume these are from various plugins that have been installed and then removed over the years (almost decades).

I’d like to remove them. Or should I honour “if it ain’t broke don’t fix it”?

These are my extra tables.

  • auth_sources
  • books_for_review
  • books_for_review_authors
  • books_for_review_settings
  • captchas
  • comments
  • dataverse_files
  • dataverse_studies
  • edit_assignments
  • group_memberships
  • group_settings
  • groups
  • metadata_description_settings
  • metadata_descriptions
  • metrics_old
  • mutex
  • notification_mail_list
  • object_for_review_assignments
  • object_for_review_persons
  • object_for_review_settings
  • objects_for_review
  • paypal_transactions
  • processes
  • referral_settings
  • referrals
  • region_mapping_tmp
  • review_object_metadata
  • review_object_metadata_settings
  • review_object_type_settings
  • review_object_types
  • roles
  • rt_contexts
  • rt_searches
  • rt_versions
  • submission_artwork_files
  • submission_supplementary_files
  • submission_xml_galleys
  • theses