". . . there would be 10,000 or more messages about it already. . . ."
There seem to be quite a few, already, or at least something related. https://discussions.apple.com/thread/4755486?start=0&tstart=0
THIS is "quite a few": https://discussions.apple.com/thread/3391947
As are these:
And older ones:
As you can see, battery issues have been common since the first iphone, frequently reported after an upgrade, but not always. So to blame a specific version doesn't describe the problem sufficiently to find a resolution.