English YouTube video by a Chinese bilibili channel HTX studio doing phone battery testing, testing every phone for 500 cycles in different conditions

These guys tested three phones per bucket for 500 charge cycles. Tl;dw:

iPhones lost 11.8% when slow charging for 500 cycles, 12.3% when fast charging, and 8.3% when fast charging from 30% to 80%.

The IQOO phones lost 8.8% when slow charging for 500 cycles, 8.5% when fast charging, and 6.0% when fast charging from 30% to 80%.

Only using half the capacity does make a difference, but you'll only see longevity differences after multiple years, and only small differences then. These tests took 167 days, but the phones were charged and discharged 3 times a day on average, running heavy software to drain the phones quickly.

What I assume to be the reason for the difference between iPhones and Android phones is the maximum battery capacity. The iPhones started out with a much lower capacity battery to begin with, and even now iPhone batteries are sometimes pitifully small, so any wear and tear is magnified.

Also nowadays there are silicon carbon batteries which haven't proven their longevity yet. There are rumors about lower longevity, because they expand and contract more during use. There hasn't been independent testing to verify that yet. What has happened is that multiple Chinese phone generations have had silicon carbon batteries, and now even Samsung is offering phones (new z fold 8 line, soon S27 and more) with a small amount of silicon carbon, increasing the capacity about 10% beyond what lithium would provide.