Override iPhone's automatic brightness adjust?

Apple seems to have completely removed the automatic brightness switch in recent iOS versions - the only 'automatic' settings now are for light/dark mode & Night Shift. I don't mind Night Shift changing my screen's white point as night comes on, but in regular daylight I heartily object to it constantly deciding for me how bright the backlight should be. I'm reading my book, it feels a bit dim for the ambient light I'm in, so I quickly dial the brightness up a bit…. then as I'm reading I can see the system just overruling me & turning it back down again. So I turn it up… the system turns it down. Rinse & repeat ad nauseum. I really do feel it's something I ought to be in charge of. Does anyone know the magic dance necessary to stop it doing this? Picture of settings just in case I missed something really *really* obvious.