Hopping in to add some additional feedback since Iluvatar invited further comments.
As of my last eye exam, I had good vision. I stare at tiny letters on a tiny laptop screen all day for my job. (Reading text on all kinds of backgrounds comes with the territory, and reading small text is part of the schtick.) The computer I play POTM on also has a built-in brightness booster that adjusts for each program so I can always see.
And, unfortunately, I'm still struggling a bit with the OOC text, like many folks here.
Some accessibility recommendations I've seen suggest using text colored in tertiary/mid-tones between primary and secondary colors for a variety of backgrounds (especially dark ones). They create a clearly visible color while also accommodating colorblind readers by relying on a mixture of colors instead of one dominant color. If those are too gonzo, would it be possible to push up the luminance on the current OOC text so it's brighter?
It's great to see the team making this change to give players visual cues between different chat modes. Thanks for doing that, and thanks for inviting feedback from the community on how to improve it.