It's not weird for 1000 users to be simultaneously connected via the same IP because of CGNAT. This is where you would have to do something like browser fingerprinting to try to work out if they are the same person.
Browser fingerprinting works best on the Wintel and Android ecosystems, but fails on apple's devices because they are extremely uniform, and apple has been working on making them even more uniform. As apple products are designed to be used on apple devices first (and I guess also tested on them first), it would be unlikely that they employ fingerprinting.
