I had a field in a form called “last_name” and a label with text “last name” .
When I switched to the browse mode the label was changed to the value in the last name field.
I have no merge fields written within the lable text.
I deleted the label and added a new label similar to the previous one but I could not reproduce the problem.
I thought it is better that you check that this is a hidden bug…
Hameed