Results or Methods - What comes first in discussion section?
In short: the assumption that the discussion of results always comes before the discussion of methods is wrong. There are no rules.

The purpose of a separate results and discussion section is to keep facts clearly separated from opinions/interpretation. What happens inside the discussion section depends on your writing style and the content/goal of the paper.

For example


if your paper presents new methods there is no difference between the discussion of results and the discussion of methods
if the uncertainty in the measurement methods may have affected the results, methods and results are discussed at the same time


A possible reason to discuss results first might be that readers are most interested in the results. Unless your paper is about the method itself an expert in the field probably knows the methods already. But as said, there are no rules.