register_taxonomy capabilities not taken into account with metabox

[BjornW]

When registering a new custom taxonomy with register_taxonomy() I use the following capabilities array in the registration:

<?php      
'capabilities' => array(
  'manage_terms'  => 'activate_plugins',
  'edit_terms'    => 'activate_plugins',
  'delete_terms'  => 'activate_plugins',
  'assign_terms'  => 'edit_posts'
),

Users without the capability 'activate_plugins' are not shown the custom taxonomy in the main wp-admin interface. However they are still able to add new terms in the metabox shown in the custom post type connected with this custom taxonomy, which is not what I'd expect. I'd expect users to be able to assign existing terms, but not to add any new terms.

[BjornW]

Annotated screenshot logged in with role admin

[BjornW]

Annotated screenshot logged in with role editor

[BjornW]

Tiny plugin to demonstrate the issue

[grapplerulrich]

I think this is a duplicate of #26409

[johnbillion]

Duplicate of #26409.