Hi! Please help me with the battery and sleep problem on my MacBook 2015.

Hello! Please help me with my Macbook pro 2015 mid. My computer is always on charge (during the day) and at night, before going to sleep, I unplug it, lock it and press the cross (put it in sleep mode). So, the last few days the macbook has gone from 100% overnight to 0%, and it's really frustrated me. Before that the battery discharge was from 100% to 70-80% assuming I had 700 charge cycles.

Please help solve the problem, as well as adjust the pmset properly so that the battery works steadily when disconnected from power.

I am also wondering if I can keep the macbook on charge for a long time while working with it?