K - this makes sense then! Hopefully the weather picks up! My driving habits have changed so much since getting this car!! It’s almost become a game to get the best mileage I can!
I have a 2021 Clarity Touring with just over 8000 miles/12,900 km. I live in Vermont, so cold weather is the norm from November to March. I play the mileage stretch game, too. But I do not experience that great a drop with outdoor temp drop. My car is in a covered shelter with no doors, kind of like a wind tunnel, but roughly the same temp as outside.
Unlike your Clarity, my battery bank is only 18 months old, so that may account for the difference I see. My range has not gone below 47.2 mi. / 76 km. when we dipped into the teens F. In addition to a newer battery pack, I try to charge the car in cold weather when the daytime temps are warmer. [I have solar, so there's lless guiilt when I charge during peak hours.] I also pre-condition the car before driving on cold days, run the seat heater, and go easy on the climate system. However, if I need to go 100 miles north on the interstate, I use climate and the ICE engine in hybrid mode. I've had 2 such trips recently. And as you also do, I use very little fuel. [25.558 gal. / 96.75 liters in 8009 miles. I just filled the tank.
In another 3 years, I suspect my numbers may look more like yours are now.