TL,DR summary: Change the comment text color to #84A0A0, as suggested by Kaldari below, in T170067#3440124.
The <!-- comment --> text is currently rendered in #AAA text, which is drastically under legitibility standards https://snook.ca/technical/colour_contrast/colour.html#fg=AAAAAA,bg=FFFFFF
Comments are often important information directed at editors, and should be clearly legible.
- Comparison with the other 2: https://meta.wikimedia.org/wiki/Community_Tech/Wikitext_editor_syntax_highlighting#Color_and_style_guide_.28with_comparison_to_.22Syntax_highlighter.22_and_wikiEd.29
- Skimming some search results, the most common white-background schemes use medium-grey, or blue/green, or red, for comments.
- https://medium.com/@MrJamesFisher/your-syntax-highlighter-is-wrong-6f83add748c9 (Section #1 is all about comments coloring)