Oh! It’s so obvious [heavy sarcasm; it’s not at all obvious] that I need to touch the clock display to find lighting options! I’d been looking under all the options in line 2: font, book location, bookmarks, search, more>settings (see pic 1) and couldn’t find normal brightness settings.
If I touch the TIME, I get the options like DNSB pictured, and I’ve now turned off the auto- brightness.
Who created these new “brilliant” (not) menu options?!?
Thank you for showing me screen pics, which let me know those options still existed somewhere!
Pictures to be uploaded shortly, from computer. IPad has trouble after the “upload images” button, and never returns! Hmmm -- I'm not getting the images to add from my laptop either. On a zoom call right now; will try harder in an hour.

// No can do. Wonder if that's my M1 mac and extra Safari protections. Oh well; never mind the pics.