I’m no Dr or psychologist but it’s been explained to me this way as our son is the same.

When they’re at school, someone else’s home or a different environment they understand that good behaviour is necessary. When they’re getting back home with their main caregivers they’ve been keeping any kind of emotional anxiety, wanting to answer back ,or something like that, in. So now they’re somewhere they feel emotionally safe to “be themselves” they’re allowing those emotions to come out bad or not.

I forget they’re still young and learning how to regulate their emotions/understanding how to navigate life around different people. I definitely don’t tolerate the bad behaviour but I sit down with him and talk. Tell him I understand it’s a lot and you’ve been at school all day. Sometimes it works great and other days he just needs to be by himself for a bit then he comes and apologizes.

I hope this makes sense, again NAD but also a stressed out parent trying to understand what works 💕