Changing depth of field?

I may be imagining things, but i recently switched my camera (arducam) from auto exposure to manual exposure, and it seems like the depth of field has gotten smaller.

Like the articam doesn’t have the ability to change the aperture, correct? So changing the exposure shouldn’t affect the depth of field at all. But it seems like at the same focal distance things especially closer towards the edge of the field of view seem to be a bit blurrier than before.

Am I just imagining things? Or is there something where we can actually change the depth of field?