Inconsistent charging of 2017 MBP 13" (A1708)
Sometimes, your mac will do this to preserve the battery. It learns from your charging habits and will wait to charge past 80% until you need it. for example, if you go to work every day (ok, maybe not right now during covid) at 8 o clock, and have your mac charge the entire night, it will charge to 80 during the night, then at around 7 o clock, finish charging, and by 8, it should be at close to 100%.