Many fonts don’t have super script and sub script support, so they’re disabled (at least all the font I need to use).
I know some fonts have built-in symbols for TM, SM, R, C, etc, but in many cases, they’re not superscripted or inconsistently so.
It would be great if Figma supports faux Super Script, where you can highlight any characters, make them smaller, and adjust the positioning. (similar to how our engineering friends would implement it using and CSS to fine tune)