For sure, but it doesn't need to be a major handicap if they're used correctly (i.e. don't do what Russia did in its initial invasion).
Western military dominance is based on relatively small numbers of technologically sophisticated weapons platforms, sometimes so technologically sophisticated and therefore expensive the production run ends prematurely (F-22) or there's serious doubts about the sustainment budget and the affordability of giving pilots adequate flying hours to stay sharp (F-35). The Chinks don't need to have the best planes, tanks and ships in the world, they just need to be close enough to be competitive and have enough of them to absorb attrition. They're getting there, especially in naval and missile forces.
So, pretty sure the J-20 is inferior in every way to the F-22 and F-35. But can it absolutely ruin your day if you're in an armed conflict with China? Yes. It's not exactly Leon Trotsky's quote about quantity over quality, but if your homies bring a couple of gold-plated, laser-guided baseball bats to the fight and the other guys have forty cheap wooden bats between them, they're probably gonna deliver the beat down.
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