Discovered while testing MC-269437.
The bug
The black box which is displayed around the currently selected resource pack or data pack in the resource pack or data pack menu does not appear to be retexturable.
I had initially assumed, due to the black center and white border, that this used either the text_field or text_field_highlighted widget textures, but changing these via resource pack has no effect on it.
How to reproduce
Download and apply the attached resource pack
Enter the resource pack menu
Click on a resource pack
Expected results
The box shown behind the clicked resource pack would look different from how it usually does.
Actual results
It remains completely unchanged.
How to fix
Instead of pointing this to the text field texture, it may be better to use a different, dedicated texture for this instead, since it isn't an editable text box.
Linked issues
relates to 1
Attachments
Comments 2

Affects 1.20.5 pre-release 1 and pre-release 2.
Can confirm