It depends for how long this has been going on. If it was for more than 3 months I would discuss it with someone.
Hey mama, SLP here! You’ll never regret getting intervention too early, but you may regret waiting. He is still young, but you know your baby best and if you have any concerns, it’s worth mentioning to his ped.
My son did this at 15/16 months, professionals told me “hes young, hes probably regressed due to a new baby” now hes on the waiting list to be assessed for autism. You know your child best, if youre worried, id definitely contact a professional dx
Omg my 13 month old has done the same, stopped saying Mum, Dad and Nan and says no other words anymore. If there are no other signs it may be that he will pick them up in some later months again. My little boy is under investigations for possible delays though with other signs linking to global developmental delay, cerebal palsy and autism. If he cant meet his milestones then its worth seeing your Gp who will make relevant referrals to child paediatrician etc x