up to Unity 2022.2.18 I have worked using literal unicode values in different text areas in inspectors, these in combination with a nice icon font like fontawesome and TMP work great, here is an example:
you can see that I can put the literal “\uf357” there and it renders as the shield icon in scene
this behaviour changed in u2023, at least in 2023.2 and unity 6.
Now the moment I finish typing the “\uf357” the textbox instead of retaining the literal “\uf357” characters it replaces them for a rectangle symbol:
the shield icon still shows in the game, the problem is that the rectangle symbol is useless, you can’t copy-paste it (if you do, you paste the rectangle symbol and not the original unicode value), you can’t recall which unicode it was for that shield icon, I think the old behaviour is way more practical and useful.
Also this also happens in other textboxes and string inspectors along the UI, so it’s probably not a TextMeshPro issue.
Can we revert this back to the old behaviour? is this configurable?
EDIT: its interesting how if you enable the RTL editor in TMP you can still see the unicode value there but inversed 
