My son is pooping in the bath

Maybe spend time sitting on a potty have a rewards chart read a book. Is it just they feel relaxed in the bath and then poo how old is your child?

Does he have a poop schedule? Does he poop every day at that time? You could say no bath until you poop. Knowing that’s his schedule and he will likely poop in the bath. Just keep it casual don’t force it but say firmly “I’m not giving you a bath until you poop” then keep an eye on him and see if any poop cues come on then tell him to go potty. A night of no bath is gonna be okay, just wipe him down before bed (if no bath) but let him know, mummy means business. You ain’t bathing until you poop

Ill try. Im scared to traumatize him. I dont want to push it before he is ready.

I wonder if it's the warm water that relaxes him. Maybe try to incorporate some warmth when he tries. Like a rice sock or one of those warmies.