For a number of reasons, which I already described in my last post:
1. Pictures at SAC have always been more difficult to come across than CAC -- think about how many high quality ground photos of new SAC Flankers or FC-31 airframes we've had taken from SAC over the years
2. The emerging strategic competition has caused the release of new pictures and new information of weapons developments to be reduced across the board as well across multiple domains.
So yes, the pictures of J-XY/J-35 that we've had so far very much is entirely reasonable and expected at this stage.
As for the existence of J-XY/J-35 -- it very much is irrefutable.
We have pictures of it from a number of different angles, all consistent, all in the context of years of consistent rumours and the grapevine positively identifying said pictures as the aircraft long expected.
For PLA watching of new aircraft, it meets the standards of being irrefutable.
Seeing as you brought up J-20, let's take a look back at when its existence became similarly "irrefutable" to the way J-XY/J-35 is now.
Arguably, it would have been in late December 2010, when we had a couple of pictures of about this quality (similar in quality to our J-XY/J-35 pictures that we have)
Similar to J-XY/J-35, the emergence of J-20 and the release of its initial pictures was accompanied by years of credible rumours, where the configuration and planform of the aircraft was virtually confirmed, and where the release of its pictures was carried out by a few different angles, with the grapevine at the time consistently saying "this is it, this is what we've been expecting".
Let me be clear -- a new aircraft's existence meeting the threshold of being "confirmed" has never depended on the release of high definition imagery.
If you are asking "well it's been months now, so where are the higher quality images of J-XY/J-35??" -- my answer are points 1. and 2. that I described above.
Moreover, the threshold for the aircraft's existence has already been met -- you cannot question the aircraft's project after the fact simply because we haven't had a regular flow of high quality pictures, that isn't the way it works.
Firstly, China has developed almost ten or more types/variants of military aircrafts during the recent 15 years. For most of the military aircrafts which were fially proven to be real, they were always leaked with photos when flying or parking, taken from afar or near places, with full resolution of the camera.
Even the KJ-600, although never been taken photos on the ground yet, has their photos taken when they were in the air, with enough details and natural background scene to confirm the variant to be real.
But for the new FC-31 carrier-borne variant, I didn't see any full size photo taken naturally when it was in the sky or on the ground with sufficient detailed background to identify its new special characters like hump back fuel tank, or sweepback vertical stabilizers. There are either low res photos in the sky with no details, or green images with details but look suspicious in a blurry background, unlike any photo you could snapshot with a phone or digital camera of the 2020 era, but an beginner's work of photoshopping.
Secondly, for all proven military plane of PLAN, the always built several prototypes for frequent test flight.
J-20 had her no. 2001~2017, 2021, 2031 prototypes.
Y-20 got the no. 781~783, 7810 prototypes.
J-15, also developed by SAI, had her no. 551~556 yellow prototypes witnessed.
And the KJ-600 too seems to have at least three airframe for test flights via Google Earth.
If FC-31 naval variant was decided to be developed, when will we see more than one prototype flying over the sky?
It's not a matter of secret keeping. When the aircraft flies in the air, everybody would see it. Even the J-20 was not hidden from the public since its first flight. There could not be invisible prototypes flying without focus.
Thirdly, for all the prototypes of J-20, Y-20, J-15, J-10 and other military aircraft, we always saw the the emblem of PLA, or a national flag painted on the plane. But for all the photos of the FC-31, including the most recent ones, we didn't see any of the official tag on it.
This may be a circumstantial evidence, but I think it is meaningful.