Current UUVs that are routinely lost and fished up are wave gliders designed to be disposable.
China has been making a lot of breakthroughs with underwater communications that might make large sized UUVs viable with current AI. Especially if operating in the shallower parts of the SCS.
But this design is such a close match to the MC209 model sahureka posted that it’s almost certainly that.
That's just your speculation. It's a big leap to apply their breakthroughs on a sub of such scale. I suggest you read what the others have been discussing about this sub.
Is the MC209 unmanned?