Somebody said it is not WS-15, There are new WS-10 variants with TVC more like the kinds we had seen in J-10B.
We've had rumours that J-20 flying with a TVC WS-10 since Zhuhai 2018.
These pictures that Deino posted have all been more recent, released between 2021 and now.
While it is theoretically possible these could be new WS-10 variants with TVC, we cannot ignore the elephant in the room that over the last year in the same timespan, there have been significant noises about WS-15 starting flight testing with J-20.
It is also possible that these are old pictures only being released now, but the timing is also very suspect and somewhat confusing.
Of course we should all wait and see, but all PLA watching is a result of correlating rumours with pictures, and the current situation is one that is worth taking seriously.
Additionally, with the most recent picture of the "short nozzle"/new engine that Deino posted, we can see that the air intake (and possibly even the ventral wing/fuselage join) on the same side (right side) appears to be different from the left as well, which would be somewhat suggestive of a somewhat more different engine in terms of structure and performance characteristics.
(Likely a modified early 2011-2013 prototype airframe?)