The User#visible_environments method added in #17463 has a spelling mistakes in the view_environments permission name: https://github.com/theforeman/foreman/commit/273f928#diff-4676c008b11a5480d73d4a6de01e45b9R388

This will probably cause no environments to be visible to non-admin users.

Though untested, it may have the same effect as #18995 and cause the importer to try to remove invisible environments rather than ignore them.