The datasheet does not necessarily reflect the complete marking. Probably only ST can answer your question - this is a primarily user-driven forum.
> is it fake?
I haven't heard about outright counterfeit 'F407 so far, but then the definition of "fake" may be very wide, ranging from "can't work at all" (e.g. an empty package or remarked completely different part) through "mostly or partially functional but different manufacturer, re-marked", "genuine ST but not the specified part, re-marked", "genuine part, genuine marking, but dubious origin (e.g.stolen)" to down to "genuine part, but mishandled during storage".
The only answer to that question is the one you don't want to hear: not fake, if you acquired it from as reputable source.
JW
