07-04-2019 03:22 AM
Dirty sensors tend to create dark grey smudges. I think you need to take more test shots. Those spots could be birds.
07-04-2019 06:17 AM
They could be hot/stuck pixels but to be sure you need to take a shot of a completely blank plain surface ( a sheet of paper), it is better if the shot is completely mis-focused then faulty pixels will still show up as sharp spots, do not use the sky there are too many things floating about in it.
Enlarge the picture to 100%, make a small crop of the problem area then post it on here to get a proper diagnosis.
07-04-2019 06:19 AM
They appear on every photo. It was clean for a period and then suddenly something happened...
If they appear in every image, no matter which lens, then you could have a sensor issue. Sensor dirt tends to be way out of focus, so it shows up as translucent smudges. Hot pixels tend to show up as distinct pinpoints, though. If it is identical in every image, then I would rule out a bad memory card.
Contact Canon Support.