Sleep mode not working correctly anymore?

Hadn't used my Edge 530 since the fall.   Charged it last week and used it.  It updated to the latest 5.1 version and GPS.  Seemed to work fine.   Recharged it to 100%.   Used it on 3/16/2020.   It was down to about 70%.  Put it in Sleep mode.  Went to ride 24 hours later and the battery is dead.  Charged it again to 100%.   Put it in sleep mode overnight, 8 hours.   Woke up and it wouldn't turn on.  I had to hold power for 10 seconds.  Then it turned on, but battery was down to 60%.   Is this normal?    Should I just stop using sleep mode?  I remember sleep mode working better last summer.