The page editor throws some errors in the console:

Format "core/subscript" is already registered to handle bare tag name "sub".
Format "core/superscript" is already registered to handle bare tag name "sup".

This is due to our scripts trying to handle the tags "sub" and "sup" in assets/src/RichTextEnhancements.js .

We can check if our script is still relevant, and either remove it or find a way to register our handlers into the block editor without errors.