Steps to reproduce the issue

1. Create a Category:
   1.1. Navigate to Content > Categories > New
   1.2. Set the category title and then click 'Save & Close'. No other field entry is required.

2. Create a new custom field: Navigate to Content > Fields.
   2.1. Navigate to Content > Fields
   2.2. Select filter dropdown at the top of the page (which defaults as Articles) and select Cateogry.
   2.3. Click (+)New to create a new field.
   2.4. Set the title, remove 'All' from the Category field, and add the newly created category. The field type will default to text. Save & Close.

3. Navigate back to the newly created category (Content > Categories) and select it for editing.
   3.1. You will notice the new 'Fields' tab appear with your new field. Enter some data into the new field and Save.
   3.2. Now change the publication 'Status' to 'Unpublished' and then save.
   3.3. Notice the bug: the 'Fields' tab has disappeared. It will return if you change the status to 'Published' and click 'Save' again. The data however, will now have been cleared.

Expected result

At stage 3.3 the 'Fields' tab and the custom field should remain after saving the status as 'unpublished'. One can reproduce a desirable outcome only if they leave the 'All' option in the Category field on stage 2. In other words, changing the category to a specific category will create this undesired outcome.

Actual result

At stage 3.3, the custom 'Fields' tab should remain, along with its data, regardless of the 'Published/Unpublished' Status.

System information (as much as possible)

Joomla! 3.9.21
PHP 7.3.23

Additional comments