If those numbers are so big and growing, how come Apple’s iOS share fell from 23% worldwide last year to 16% this year (worldwide)
I can think of a couple of reasons.
1) Occam's razor suggests that the research may simply not be that accurate to begin with, and Apple's true market share is nowhere near as bad as what you are suggesting. You are basing your entirely argument on one website's info, and really, only Apple themselves knows how many iPhones they have sold. Which brings me to my next point.
2) There is little doubt that the number of active iPhone users continues to grow in the world, based on Apple's own reporting (which should be the most credible). So even if Android smartphone share is somehow growing at a rate faster than Apple's own (which I find suspicious, given how saturated the whole smartphone market is already), I don't see what exactly the issue is. More people continue to buy and use iPhones, the nature of the apple ecosystem means that these users will in turn go on to purchase other Apple products and services, and Apple is in a unique position to capture the profits from revenue spent on their platform (unlike say, Samsung, which earns no money from an app purchased through the Google Play App Store).
3) What I suspect is really going on is that researchers are attempting to use device sales as a proxy for market share, which is inaccurate to begin with. Like say someone buys 3 cheap android phones over the same period of time as another user keeps his iPhone because the former is cheaper and therefore spoils faster. It sounds like android market share is growing twice or three times as fast compared to Apple, whereas in reality, it's still the status quo (when you base it upon 100%).
Likewise, a lot of the doomsaying that people have been claiming over the years simply hasn't materialised. Even if app developers are more unhappy with how Apple is treating them, it doesn't mean they are now embracing the google ecosystem, because Apple still commands the lion's share of profits in the industry (by virtue of having aggregated the best customers in the world). And I believe that companies like Meta and Google have said on record that iOS is still more profitable for them despite Android's larger market share.
Market share isn't quite as meaningful as usage share in this scenario, and I find that Apple's foundation continues to be rock solid in this case.
Frankly, I see nothing to worry about from Apple's perspective. You can rattle off all the hardware specs you want (I seem to recall one member going "Threadripper! Threadripper!" when Apple Silicon was announced for the Mac, and well, look at the state of Intel today.
We will see whether this translates into meaningful sales figures in 2025 or not, but I wouldn't hold my breath if I were you.