Why does the print speed change at specific height? (Using Ultimaker Cura slicer)
Not being able to see the rest of the model (from the first image), if looks as if the light green sliced area displaying a lower speed for the top of the cylinder, is the only part that need to be printed to that height (now confirmed in the second image). This speed reduction is done by the slicer and is not specifically caused by Ultimaker Cura (other slicers do result in similar behavior). Note this is a good thing! Lets explain.

Filament needs an amount of time to cool before the next layer is deposited onto the previous layer. When the layers get small (surface area) and there are no other layers the print head shifts to, the print process is slowed down to allow the filament to cool down; hence you see a decrease in print speed.  If you deposit too fast, the last part of your print will become too hot and will deform.

A print parameter that influences the behavior is the Minimal Layer Time parameter in Ultimaker Cura, please read the hint information of this parameter: