Yes, I only changed the cursor position... Here is another example with the snow accumulation overlay:
When I click on the map, the cursor appears and it shows 55.2 cm:
After dragging the cursor around a bit it shows 16.6 cm at the exact same location.
The values seem completely random to me as I sometimes get 33, 18, 5 or even 0.0 cm at the exact same position. It's very weird...