"Formatting preview" and Syntax highlighting in RAW comments

Before I get started, my apologies for the incorrect terminology. "Formatting preview" is probably the wrong word. Another thing, I have a lot of difficulty answering advanced questions for two very small (but also very similar) feature proposals. Lastly, A lot of questions sound very similar to me, so my apologies for having the same answers.

Problem to solve

GitLab still doesn't support formatting preview and syntax highlighting in the comments.

Intended users

Everyone

User experience goal

It's easier to tell what everything is.

Proposal

I don't know how to solve this problem technically, but here's a picture of how Codeberg (Gitea) makes it look:

Further details

As said above, it is easier to tell what everything is, instead of switching between "Write" and "Preview" constantly, it will help us be more efficient on writing comments.

Permissions and Security

I don't think it requires additional security.

Documentation

I don't think it requires a user to change the documentation.

Availability & Testing

I will need help here.

What does success look like, and how can we measure that?