This isn't a bug that started in 1.19.50, but began back when 1.19 first released. It is not as bad as it was then, when the world generation was horrendously slow, and the game lagged and froze constantly. At that time, I was on an iPhone 8, and despite its age and older processor, it had run 1.18 on 12 chunks without much lag, whereas when 1.19 launched I had to put it down to 5 chunks and turn off fancy graphics and smooth lighting just to make the game playable.

Fast forward a few months when I got my current phone (an iPhone 12) and its processor is much more powerful and more efficient with more GPU cores. You would think that it would be able to run 1.19 just fine, right? Well, I guess not, because for the game to run smoothly, I have to have the render distance at 8 chunks or below to prevent major fps drops. On 10-13 chunks, the game drops frames quite a bit, and the phone gets extremely warm.

I watched a video from just 2 years ago where a person was playing Minecraft on an iPhone 12, and at that time, the max render distance was 36 chunks, and he loaded up a new world and was running around, but the phone was not lagging at all. What, then, changed so drastically? In just 2 years the game got so laggy that a device that could previously run it at 36 chunks max with no hiccups now cannot run it at 13 chunks max without have major fps drops?

I hope someone on the Mojang sees this, and I also hope they optimize the game better