Problem identified

The parameters of different back-end forms are not consistent.

Article edit form

Content > Articles > create/edit an article

The Publishing tab has Start Publishing + Finish Publishing, and also Metadata

Menu Item edit form

The Details tab has Start Publishing + Finish Publishing

The Metadata tab has Metadata

Proposed solution

Check all Joomla core components,
compare the parameters to see if they are used in a consistent way.
If not, make changes to make it more consistent.

In the case of the Publishing fields in the Menu Item edit:
On the Menu Item edit form, change the "Metadata" label to "Publishing"
and move the "Publishing Start" + "Finish Publishing" to that "Publishing" tab.