3 months baby sleeping on tummy

My 3 month old baby is already able to flip and roll since 2.5 months. But the worrying thing now is, he now prefers to sleep on his tummy. I wld always put him down on his back but somehow in his slp he will turn to his tummy or sleep side lying. Whenever I see it, I'll turn him to his bck slowly but tt's when he'll wake up and started crying and it's hard to get him to sleep again. I've ever let him sleep on his tummy while monitoring him the whole time and he cld sleep a solid 2 hrs nap, as opposed to just half to an hour in the afternoon. Both my mom and MIL said can just let him slp on his tummy as long as nothing ard in his cot tt can suffocate him but I'm just so worried esp at night cz sometimes he look like as if he just faceplants himself on the mattress. He wld usually sleep for abt 5-6 hrs at night. Do any parents let ur baby to sleep on his/her tummy, especially through the night? #1stimemom