After a few days of heavy traffic on one of my sites, I'm seeing a few of these errors in my logs:
Notice: Use of undefined constant i18n - assumed 'i18n' in metatag_admin_settings_form() (line 692 of backdrop/modules/contrib/metatag/metatag.admin.inc).
After a few days of heavy traffic on one of my sites, I'm seeing a few of these errors in my logs: