Poop withholding - need advice

My 2, almost 3 year old has started holding in his poop and refuses to use the toilet. He instead holds it in and waits for the sensation to pass. Sometime he has streaks in his underwear from holding it in. If you ask him to use the toilet he refuses and says he doesn’t have to poop. He’s been potty trained for 6 months and was successfully using the toilet up until a few weeks ago.

Anyone else been through this? How did you get your toddler to get back on the potty to poop?

We’ve had many talks and he says he doesn’t want to poop, when I’ve asked if it hurts he says no.

Any advice would be appreciated. Thanks