CSS Exfil Protection

Breaks gmail theme

Starting a couple weeks ago, I noticed the gmail theme was not working. A bit over a week ago, I tried to get help through Google One. They had me clear my cache, and then it was fine. Then the next day, it was gone again. This time, they had me uninstall Chrome entirely, and reinstall it. Fixed. Next day, not fixed. That time, they had me reset all the Chrome settings to default. Fixed. Next day, not fixed.
After each attempt at fixing it, I would do a hard refresh, so I finally realized that was probably the thing that was actually fixing it. So yesterday and today, when I came to the computer and the theme was gone, I did a hard refresh, and the theme came back. Today I experimented, doing a standard refresh, theme disappeared. Hard refresh, theme came back. Standard, gone. Hard, back.

I tested, turning off Chrome extensions one by one, and trying the hard and standard refresh. When I turned off the CSS Exfil Protection extension, the theme just worked completely.