You have to retrain your brain to “accept” 77-83 G1000 being the “same” as 80kts analog.
Understand that an anolog instrument has hysteresis. Look it up.
Your speed is fluctuating just as much as it is with the G1000, it’s just within the error of the instrument which makes it look like you’re at constant speed.
Im taking a couple of intellectual shortcuts here for simplicity sake.
The G1000 speed tape has the same color indications.
With an analog instrument you glance at the angle of the needle. Straight down 6 o’clock position is close to 100-110kts in a C172.
so without reading the number on the scale you can determine if your speed is safe.
5 o’clock too slow, 7 o’clock too fast and 6’ o’clock is good.
Stop staring at the numbers, look at the relative position of the speed bug.
Flying is dynamic not static.

Pick a random number and keep dividing it by 10, for practical purposes you’ll reach zero, mathematically you don’t and never will.