Likely not helping the look of the monospace font is that it’s using system defaults for --d-font-family--monospace, unlike the default base Inter in --font-family. At 14px (the font size for code blocks), it looks fine, but at the font size of the text editor, it feels weird next to Inter.
Firefox - Windows
Firefox - MacOS
Safari - MacOS
While this behavior of falling back to system defaults matches other coding focused sites like GitHub and StackOverflow, it’ll probably be better to find a specific monospace font that pairs well with the default Inter body font.