Both of your statements are completely wrong.
1. Official agencies of both India and Pakistan love to engage in wars of words. They often use unrealistic and false statements to intimidate each other. These statements do not represent their true views and true capabilities.
2. Weapon systems are a very large subject. No one can know all the knowledge. Whether it is a soldier, a designer, a skilled worker, a military fan... they only know part of the knowledge in their respective fields. This is a completely different field. What anyone in the PAF knows does not overlap with what military fans know.
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About J-20.
China has not completely banned the export of J-20. So far, the only official report was in 2016, when Ma Xiaotian, then commander of the PLAAF, said: "ē®åę¼-20ęę¶ę²”ęå¤éč®”åļ¼ There is no plan to export the J-20 for the time being!"
But the J-20 is not suitable for the PAF. You can end the discussion about it.