Hello Mateusz Konieczny,
Thanks for reaching out with the question.

After checking the history, I noticed that this edit was made about two years ago when I was still a new mapper. At that time, I was also working on the Hasiru Aqua Small Pond Mapping – Karnataka, India Part 2 project
(Project link: https://tasks.hotosm.org/projects/14659/instructions), where the instructions specifically required using man_made=pond. It seems I unintentionally carried that tagging over while switching between tasks.

I agree the correct tagging here should be natural=water + water=pond. I updated the tagging to reflect that.

Thanks again, if there’s anything else needed just reach out.