Describe the bug
Removing a Template Part from a page results in the Template Part edited to clear all inner content. This is a 'recent' regression in behavior. @noahtallen mentioned this is likely related to a recent PR of his (#21368 ).

To reproduce
Steps to reproduce the behavior:

1. Go to an Edtior (shown below is page editor) with full site editing experiment enabled.
2. insert a Template Part.
3. remove the template part.
4. notice the template part is 'dirty' in the save panel, and re-inserting will result in an empty template part.

Expected behavior
Expect the template part to not be dirtied on removal.

Screenshots