I think I speak for the majority of Quest 2 owners when I say that a brightness slider is such a basic, QoL feature that it's unimaginable it's gone missing. When I see suggestions to people with a problem with the brightness to "wear sunglasses" or install a hit/miss settings .apk I feel like there's a level of absurdity and we passed it. Please please please give Quest 2 owners the ability to dim the backlight...
I don't have v25 yet to verify, but I've seen people commenting that it does, and I've seen a screenshot (below). If you have v25 and don't see it, maybe try doing a full shutdown and restart (which is often needed to initialize new features after an update).