So, an update from me again :)
In the last 10 days, we had an average daily heat amount of 80 kWh and an electricity consumption of 19 kWh. That means the heat pump operates at a ratio of 1:4, which does not seem too bad.
To reduce the heat amount even further, I lowered the heating curve by 2 degrees. We currently have the problem due to the sun that we have to ventilate a lot of heat during the day (to avoid overheating at 30 degrees, the window is almost always open) and at night the heating naturally runs again at 0 degrees.
I want to compensate this effect somewhat with the lower heating curve since the sun sufficiently warms the rooms in the morning.
Let's see if it works and if I can save electricity :)