The study (if we assume it was good) told students the objective of their task was to generate a factual essay about topic X. The study then measured how much they learned about the topic at the end, but the students who used ChatGPT "learned" less and remembered their own essay less despite an equally passable essay. I want the alternative version of the study where the students are told the essay is practice, and their success will be graded on how much they've learned about the topic.

I imagine you could conduct a similar study challenging students to complete math tasks with and without a calculator and then ask them how much of their multiplication tables they've learned afterwards.

If you want to learn and grow as a person, along some dimension, you need to practice. Growing requires repetition and reflection and to experience the feedback loop of improvement. Outsource thinking for whatever task you don't want to do when the only result you care about is the only outcome. Don't outsource practice and learning if you want to improve. Only you can make the decision on when each situation applies in your day. Maybe you want to be better at some task at your job, but maybe you just need to get through the task and move on.