I don’t really see how this is practical. Is this just how code generally works or is this a RemNote only thing?
This is a performance optimization. See Large code blocks are not syntax highlighted on hover · Issue #246 · remnoteio/remnote-issues · GitHub
When you hover over a rem the WYSIWYG editor is rendered instead of a more lightweight markup, presumably to be able to put the cursor in the correct position when you click to edit etc. And this hover transformation would be laggy if you do syntax highlight for large code blocks.