I think fridges run more these days than older models.
"The manufactures stopped using the electric [door] heaters and started running a pass of the hot condenser tubing on the edges of the cabinet where the electric heaters use to be. This is often called a yoder loop tube SxS version and the yoder loop tube Top freezer version. This has now replaced the electric heaters. If you feel heat/hot around the door opening of your refrigerator you should....
clean the condenser coils as a dirty condenser can make the tubing hotter than normal
check/clean & replace if necessary the condenser cooling fan ( # F ) motor, if the condenser fan motor is slow or has quit the yoder loop pass will get very warm/hot to the touch
If the condenser coils are clean and the condenser fan motor is running ok, check the fresh food and freezer section temperatures...if the refrigerator is not operating well and the temps inside are warming up, you could feel more heat/warmth than normal."
In ‘single circuit appliances’ and appliances with a 4-star freezer compartment, temperatures are usually regulated according to refrigeration compartment temperature. When ambient temperatures fall, an issue arises because the refrigeration compartment will not need to be cooled as regularly and this means that the associated 4-star freezer compartment can then become too warm. In such cases, the refrigeration compartment is artificially heated by a light bulb or an electrical heater to force the refrigerator to cool down more frequently and thus keep the 4-star freezer compartment sufficiently cool.
I had to look up what the 'stars' mean for freezers. While the Sub Zero may not be a 4 star freezer, the concept is interesting.
Source:
https://blog.liebherr.com/appliances/my/refrigerators-heaters/
However, I did look up your fridge and you have separate cooling systems. Could it be that one runs and then the other runs during the 'off' time to save on amp draw?