iOS 17.5.1 Health App overcounting steps and miles by a lot

iPhone 15 Pro, iOS 17.5.1 I am on a hike with friends, we all have iPhones. Their phones say 10.2 and 10.1 miles at the end of the day, mine says 14.6. We started together, and walked together. Yesterday theirs said 12.6 and 12.4, mine said 16.6. Same deal, walking together.

What's up with this? Why the discrepancies?