Puppy running to strangers not in a good way

Hi, my pup just turned a year and he started running towards strangers walking by and intimidating them. When they get scared or mad he snaps them and barks at them and I cannot really control him rather than just being near the stranger and then he knows he can't touch them.

My biggest question is what is the psychology behind it and how do I effectively train by understanding this?

He's always been an introvert towards people, but recently we've been making huge progress (by asking random people if they would want to say hi, pet him, give him a treat, praises) and he now lets strangers pet him and is a brave boy. He's also a very protective dog, I've been teaching him to chill more, and trust when with me and it's been also working - like with neighbours and just simply ignoring screams outside, and it's been ok. Towards dogs he's always happy, pure, loves to meet new friends, never get into conflicts.

Usually when I let him go play with other dogs outside he wouldn't bother by anything and just play with them or listen to me if I told him to wait or return to me, but recently he spots a person and instantly run towards them, snaps, barks, most people are understanding and I escort each one of them by hugely apologizing while I cant catch him cause he's getting something like evil zoomies??

I read about training with leash, but he's not doing this behaviour at all when he's on it, like he knows it's pointless, so the only training about it I could do is pretty much off it I suppose? I know I could just simply keep him on the leash always, but I would like to trust him and work towards him being able to spend time in more pleasant ways for him, just for his happiness, what leash won't do.

I recall he had some starters of this behaviour in the past and the "punishment" by being disappointed and saying "no" was clearly not enough, I also don't think he understood returning home as a consequence of that. I really need to get to him, to be able to explain to him that the people are scared and that is a no no, and I don't know how.

I hope for some advices, and also for shared experience, methods that worked for you. Thank you.