What you might be missing is something called “maths”
Most ID.3s have a 58kWh battery, and most home chargers are 7kW, that means your charger can add 12% of your battery’s total capacity per hour.
Let’s say it’s July and your ID.3 predicts a range of 240 miles at 100% charge, that means every 1% gives you 2.4 miles of range, so charging 12% per hour translates to 28.8mph.
Now it’s December and your predicted range is only 180 miles at 100% charge, that means each 1% gives you 1.8 miles of range, charging 12% per hour this time only translates to 21.6mph.
Nothing has changed in terms of your charging rate between July and December, in both cases it’s STILL 7kW and that’s STILL 12% of your capacity.