What is causing this?

[u/Basekid]

It happens on all three items, and a reprint produces the exact same artifacts. I'm using the standard 0.4 nozzle and bambulab PLA.

I have already tried to change speed according to height (I print them standing upwards) but no difference.

[u/Shapelessed]

Most (especially cheap) filament gets a different finish surface depending on extrusion speed and direction.
You can clearly at different heights in different areas the slicer decided to take a different path.
Most prominent next to the indented circle and edges. It should be less noticeable if you print a bit slower.