Canon EOS 250D Advanced User's Manual page 199

Focusing on a subject other than a human face
z
Once the AF point <z> achieves focus, the AF point <z> will also
move to track the subject if you change the composition or if the subject
moves.
If the subject's face is significantly out of focus, face detection will not
z
be possible. Adjust the focus manually (= 212) so that the face can be
detected, then perform AF.
An object other than a human face may be detected as a face.
z
Face detection will not work if the face is very small or large in the picture, too
z
bright or too dark, or partially hidden.
The <p> may cover only a part of the face, not the whole face.
z
The size of the AF point changes depending on the subject.
z
199