LTE RSRQ RSSI phenomenon

Hi, good to be here. I hope someone can explain what is happening here.

I'm currently monitoring my RSSI and RSRQ every second of the strongest LTE cell using my moto 10 Android phone. (I use the app net monitor lite)
Then, i use a sliding window of 5 minutes and calculate the mean RSSI and RSRQ (per cell, but thats not important here)
Then, what I see is that my measurements during night time the RSRQ always goes up, and RSSI generally goes down.
Empirically I found out the cell with the strongest signal is always the same cell.

Example of my measurements of 3 nov (evening till morning):

RSSI

The y-axis is in db and the values are normalized by subtracting the mean of the entire dataset (so 4 means in that 5-minute time interval we measure 4db more than average)

RSRQ

The y-axis is in db and the values are normalized again just like with RSRQ

I hope someone can explain what is happening here?
Does the LTE cell reduce power overnight?
Or is there during nighttime less interference?
As layman in LTE i can only hypothesize what's going on here