The stair steps are all different heights

And now here it comes, who determined the height of the screed? Does it fit?

Too high at the bottom? And too low at the top.. under the stair steps 1cm is not much but it can be better.

Well, I would consider it more likely that the staircase was executed with the measurement of the raw floor but was planned with the screed height. What thickness is the screed?

And yes, fluctuations of 17-20cm are quite rough, that can be done better and does cause significant problems.

Ok, screed already in, then I revise. Photos on the phone are always a bit tricky :-/