Just like with people you need to tweak your approach when switch models--especially with a major version bump.

4.8 was the intern who lacked confidence who requires clarification. 5 is the know it all intern who fills in your spec.

As such, you need to be upfront about what you need in your system prompt or CLAUDE.me and you need to discuss your spec more up front (e.g "is there anything unclear?")

You also need to keep in mind that the intern will change based on popular demand. Most people want to one shot, so that is the default mode. If you want something else, you need to push the model in that direction.