The red dot is projected on one spot of the optic. you may move and it may look like the dot is moving. I have used reflex sights mounted on scopes for close range. The dot may not appear to be centered in the optic but if I have it on my desired point of impact that is where it goes. Same for my EoTech. try shooting some with what appears to be off center to you and check you point of impact and grouping. Your mileage may vary as you get extremely off center.
Have a nice day at the range
NRA Life Member