Canon EOS 250D Advanced User's Manual page 469

Expanded ISO speeds cannot be selected.
When [z: Highlight tone priority] is set to [Enable] or [Enhanced],
z
the ISO speed range is ISO 200–25600 (up to ISO 12800 for movies
or 6400 for 4K movies), even if [ISO expansion] is set to [1:On].
If [Disable] is set for [z: Highlight tone priority], [H] can be set
(= 137). This also applies to movie shooting (= 222).
The Auto Lighting Optimizer cannot be set.
Auto Lighting Optimizer is not available when [z: Highlight tone
z
priority] is set to [Enable] or [Enhanced]. If [Disable] is set, the Auto
Lighting Optimizer can be set (= 137).
Even if I set a decreased exposure compensation, the image
comes out bright.
Set [z: Auto Lighting Optimizer] to [Disable]. When [Standard]
z
[Low] [High] is set, even if you set a decreased exposure
compensation or flash exposure compensation, the image may come
out bright (= 136).
The built-in flash does not fire.
If you use the built-in flash too often in too short a period of time, the
z
flash may stop firing for a while to protect the light-emitting unit.
Flash exposure compensation cannot be set for the external
Speedlite.
If flash exposure compensation is set with the external Speedlite,
z
compensation amount cannot be set with the camera. When the
external Speedlite's flash exposure compensation is canceled (set to
0), flash exposure compensation can be set with the camera.
The camera makes a noise when it is shaken.
A small noise may be heard when the camera's internal mechanism
z
moves slightly.
469