Screen brightness is too high

Yes, it can go fully dark. Any level above 0 % keeps the backlight on, and an LCD backlight lights the whole glass, even where the picture is black. That is why 1 % still glows. At 0 % the backlight is off.

Brightness while you use the screen stops at 5 %, but Standby brightness and Night brightness go down to 0. For a screen beside the bed:

1. Night mode on, with Starts and Ends set to your night.
2. Night brightness at 0 %.
3. Auto standby on, with Standby after as short as you like (1 minute is the shortest).
4. If you like, Dark mode too, so the screen is black with dark cards when you do wake it.

During the night hours the screen then goes black a minute after the last touch. A tap wakes it, and that first tap only wakes: it doesn't switch the lamp under your finger.

To make it dark right away at bedtime, an automation can press the screen's Sleep button (button.press on that button's entity). The screen goes to its standby level at once, so with Night brightness at 0 it turns black and stays black until a tap, Wake or an alert.

Two exceptions: the Waveshare 4.3, 5 and LCD-7 inch can't go dark at all, and the Waveshare 7B only gets dim at 0 %. Which board do you have?

More in the manual: Brightness and standby and Night mode.