I think you are thinking of the "optimized charging" option, which tries to guess how long you will be leaving the phone on the charger and then pauses when it reaches 80% until it gets near the time it thinks you are going to take the phone off the charger and then charges up to 100%.
I think you are thinking of the "optimized charging" option, which tries to guess how long you will be leaving the phone on the charger and then pauses when it reaches 80% until it gets near the time it thinks you are going to take the phone off the charger and then charges up to 100%.