Help with trend sensor for temperature changes

Hi!

I have sauna and would like to know when it was turned on. I have a temperature sensor in the sauna and configured a trend sensor, but it look like it is not working as intended.

The trend sensor should be turned on, if the temperature within the sauna has risen by 5°C within the last 10 minutes. The temperature sensor is a Aqara Temperature sensor and it appears to update the temperature every 10-15 seconds, if it changed meaningfully. Right now it appears to turn on randomly, can someone please guide me towards a correct solution?

I switched to absolute temperature values to check whether it is on/off, but this is suboptimal due to different base values in summer and winter.

Graphs with temperature values & trend:

Sauna temperature trend sensor configuration: