Scales giving wonky body fat numbers - Found the cause

I have been using a set of smart scales for a couple of years and have bene very happy with them.
My body fat shows as between 15.8 and 16.2 every morning so very consistent.

The last 10 days or so the weight has been the same but bf has been much more like 17.8-18.8%.

Very odd. I thought the batteries might be going but normally they just go dead not provide wonky numbers.
Anyway I dug the manual out and decided to reset the profiles. Set mine up again and it was spot on at 15.8.%. Mentioned to my wife that if she had a profile set up she needed to reset it. She didn’t have a profile but she said that my 1 year old grandson loves crawling into the bathroom and pushing the various buttons to make them beep. She doesn’t take any notice of bf so she had not noticed anything wrong.