[threetwoone321]

In CS related fields, in particular ML and CV, this is absolutely not the usual situation except perhaps in the beginning of the PhD. Perhaps it's more common in fields where the research is done on top of a heavy investment in infrastructure/equipment that is lead by the professor, e.g. in physics and biology?

[astazangasta]

In my experience in biology new professors provide a lot of ideas, old professors just steal new ideas from their students and post docs.