As mentioned before, this looks like sensor dust.


To determine this is indeed the case you can take pictures of a even lit area (clear blue sky is best) with aperture 22, one fully zoomed out and one fully zoomed in or if you have a second lens take one with that one also. Download to your computer and see if the spots are on the same place.


If yes -> sensor dust. To be cleaned with swabs and fluid or if you are not trusting yourself on this, have it cleaned at a shop. Do not mess around with this, you can do damage to your cam.


Cleaning your sensor is normal maintenance, sometimes have to
perform it daily. If I had to change lenses in bad conditions on my
5Dmk1


N.B. be aware that not all dust blowers produce dust free air and produce more specs on the sensor, better to use tools designed to clean your sensor like SensorBrush