Not just worse in visual quality, I've heard many stories of friends replacing cracked screens with knockoffs who got their battery life decimated after the repair.

Many such cases probably don't connect the dots and instead just think iphone battery life sucks which is bad press for Apple.

There are two variants I've seen: LCD and OLED. I don't think they're rejects, but are instead some Chinese reverse engineering since, AFAIK, Apple doesn't sell this iPhone model with LCD displays. Plus, Apple has an iron grip on their supply chain.

They probably are inferior to the official Apple ones though (not that I'd care enough to pay 3-6x the price)

They definitely don’t go through the same quality control, the 3rd party screens I’ve bought have always had some sort of minor visual defect.