*Steps to reproduce:*
# Open a Unity Project
# Import TextMeshPro Essential Resources via Window > TextMeshPro > Import TMP Essential Resources
# Import TextMeshPro Examples & Extras via Window > TextMeshPro > Import TMP Examples and Extras
# Create a Text (TMP) GameObject via GameObject > UI > Text - TextMeshPro
# Select the new Text (TMP) Object
# In the Text Input section on the TextMeshPro - Text component, add the below text: 
_<font="Anton SDF" material="Anton SDF - Drop Shadow">Test</font>_
# A SubMesh GameObject should be automatically created as a child object of the Text (TMP) Object
# Try to delete this SubMesh GameObject by either selecting it and clicking the delete key, or right-clicking on it and clicking delete
# Observe that it doesn't delete. This is expected as the font is still being used in a rich text tag
# Press ctrl + z to undo

*Actual results:* A duplicate of the SubMesh is created in the Hierarchy, and the warning 'Child GameObject 'TMP SubMeshUI [Anton SDF - Drop Shadow]' was not registered into undo system and became dangling during an undo operation.' is logged to the console

!image-2024-12-05-12-30-09-711.png|width=975,height=41!

*Expected results:* A duplicate of the SubMesh is not created, and there is no warning logged to console.

*Reproducible with versions:* 7000.0.0a11, 6000.1.0a8, 6000.0.30f1, 2022.3.54f1, 2021.3.45f1

*Not reproducible with versions:* - 

*Can't test with versions:* 

*Tested on (OS):* Windows 11

*Notes:* 
* In 2021.3 there is no warning when undoing, but the SubMesh still doubles up. In all later versions the warning occurs