Any suggestions of what i could do ??

so ever since my baby boy was 6 months he’s been sleeping through the night JUST perfectly fine and he would get up ONCE and I would give him a bottle and he would go back to sleep like nothing, NOW my baby is about to be two years old and has been waking up at 4 or 5 am everyday day crying and not falling back to sleep until 1 or two hours later. We do the regular schedule of waking up at 8am napping at 12pm - 2pm and sleeping at 9pm. Have any mommas experience this or something like this before ? why isn’t he sleeping through the night ?