Hi 
so when you populate a dynamic it contains a lot of different components. In v4 using * could actually completly break your request.
We are looking into what we can do to still offer this convenient method but without the issue it was causing.
For now you will have to specify a populate for the component types you want to populate
e.g
{
populate: {
dz: {
on: {
compoA: {
populate: *
}
compoB: {
populate: ['some-filed']
}
}
}
}
}