I have an ongoing sort-of faux-competition with my wife about how to ask Siri for things. She asks questions and gets frustrating replies, but when I ask them slightly differently I get good data.
I think my history with software make me subconsciously better able to formulate a question for Siri in a way that produces an answer other than "I found some web results...".
I SUSPECT it's mostly specificity, or asking for simple facts ("when was King Charles born?") and not derived facts ("how old is King Charles?"), but it comes up a LOT.
That same history of software means that I don't even ATTEMPT some of the stuff Siri is notionally capable of, like maintaining a shopping list. (Though I routinely use Siri on my watch or phone to add appointments or reminders.)