From my twitter, cross posted cause I'm lazy..
On 10th anniversary of J-20s reveal, this is supposedly an AVIC official model of J-20 (alerted by a colleague).
Notes:
-6 BVRAAMs in main bay, doesn't look like PL-15 -- the new BVRAAM?
-Unsure if engines are WS-10C or WS-15
-OP said there was a cannon, but no obvious site...
Specifically this bump definitely isn't on the real thing.
It is smaller than F-35A or Su-57 gun bumps, but it is more noticeable than F-22s gun location which is *very* subtle.
Not conclusive obviously, but I'm sure that difference isn't there by accident