@hibye seems spot on about the issue, also as reported in this stackoverflow post: https://stackoverflow.com/questions/79758083/ios-26-safari-visualviewport-change-after-dismissing-keyboard before opening the keyboard, visualViewport.height and window.innerHeight match... but after opening the keyboard there's always a 24px difference (and this persists after the keyboard is closed)

We're experiencing the same issue, it seems to be a major regression