mine just changed to dark-dark-gray. It used to be a nice white. I have no idea what's going on.
Why is my interface impossible to read????

The problem is only happening with the new Analysis board for me, but the text background has become transparent so that the white text is unreadable (unless you have chosen a very dark background theme).

That part to the right of the board that has the moves and the analysis button etc. It's white on light blue.
If you have a custom theme you might try resetting it to a default one to see if that fixes the issue:
Settings > Theme

We recently released DarkMode which can look a little odd for those with custom backgrounds, or anyone who just prefers a brighter look and feel.
Anyhow, it's simple to change back to what your used to by switching off DarkMode.
You can visit here and toggle the switch in the upper right corner: https://www.chess.com/settings/themes
If you would like, I made a little video that might help you.
https://screencast-o-matic.com/watch/cqf6F8Z2NZ
That part to the right of the board that has the moves and the analysis button etc. It's white on light blue.