Common at this age
A lot of babies will transition gradually from 3 naps
to 2 right about your baby's age.
The best advice i can give you is to try to gently encourage your baby to move to 2 naps on all but the toughest days. Try to fight through that end of the day crankiness/tiredness: the sooner he/she gets used to that, the faster the transition will be complete, and the easier bedtime will be. Good luck!