If you are using schedule Charging then schedule charging are not designed to stop the charging at a certain percentage, they are designed to slow down the charging rate to slow down the battery degradation.
It will charge normally upto 80% and then slow down and it will reach 100% before the scheduled time.
Also, its mentioned that the phone will be charged before the end time.
It will recharge your phone before the end time approximately (45 mins to 1hr before)
Keep a check on battery health.