Why does VS 2019 make hash comments use a large font in YAML files?

This is more of an annoyance, but does anyone know why VS 2019 switches the font for hash comments in YAML files? I'd imagine it happens for any file using hash comments. My guess is that it has something to do with markdown, but I don't have any extensions for markdown, unless one of my installed extensions has it as an extra feature.

Here's an example:

Here's my installed extensions:

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In writing this, I looked in coderush's settings and found the answer. Unchecking this option stops the annoying (in my case -- it's probably useful to a lot of other people) behavior.

Since the question was already written by the time I figured it out, I'm posting this answer in case it helps someone else.