Galaxy Book 12 Charging Threshold?

So I've been using my Galaxy book 12 for about 18 months now, and overall I love it. But a week or two ago I noticed that it wasn't charging if I plugged it in, and was worried the battery or motherboard had gone bad.

But after a good deal of troubleshooting, I realized it would charge to 100% if I let the battery drain down to at least 96% or so. I feel like I've never noticed it do this before, but I also feel like maybe I just never noticed that there might be a charging threshold.

I am also not sure if maybe a windows update turned a threshold on.

Can anyone else confirm if this device does have a charging threshold?

 

It seems to not want to charge under some circumstances so as to preserve the battery --- it also won't charge if the cable isn't in good shape, or the charger isn't putting out the correct voltage.