The range is always an estimate based on a number of variables, including efficiency on recent trips, the ambient temperature, etc. It is not an absolute number that will always stay the same at the same percentage state of charge. That’s why people refer to the mileage display in an EV as a “guess-o-meter.” The computer’s just making a best guess of your range based on your percent state of charge and other variables like the air temperature and how the car has been driven recently. Temperature is a big factor in the winter. I’ve driven an e-Golf in three New England winters, and the range estimate drops by about 20-25% of the EPA estimate when the temperature drops below freezing. If the temps drop down closer to 0F, then the range estimate drops even further.
If you know what your current average efficiency is, you can do the math yourself in your head. For instance, if you’re at around 50% state of charge and averaging 3.0 miles per kWh, then (77/2) * 3 gives you a range of 115.5 miles if you continue driving as you are and averaging the same miles per kWh (77kWh is the max usable capacity of the ID4 battery by the way)