This also happened (happens) to me and my 2020 Model Y. When I first purchased the car I had a Google Pixel 4 (I think) and now I have an iPhone 13 running the latest iOS. My car still doesn't unlock right away about 1 out of 20 times I walk up to it. It's not really a big deal as the car usually unlocks shortly after arriving but it is kind of a pain if my hands are full and I have to fumble with my phone to "manually" unlock it.