Happens in laptops too. Its just silly. Go in the same price range and then make a judgement.
I long for the freedom of android and use iPhones reluctantly only because i really think they are a good value at almost any price point.
Same with LG, Sony and others. The only smooth Android I have ever tried was Huawei's and I am reluctant to buy Chinese telco hardware.
You can compare iphone and android performance benchmarks here [0] and here [1].
Apple devices still come out ahead of top of the range models from other manufacturers.
Yes I know benchmarks can be gamed and don't mean everything, but there is still a performance difference between top of the line Android models today, vs not only top of the line iPhones, but also iPhones from a couple of years back.
0: https://browser.geekbench.com/ios-benchmarks 1: https://browser.geekbench.com/android-benchmarks
I highly doubt a top of the line phone like the Galaxy or the Pixel would have issues with input lag.
If anything, I get annoyed by how long animations on iOS take compared to Android. Everything feels like it's running in slow motion.