[Bug Report] v-app-bar hidden after scrolling to top on iOS Safari

[derat]

Environment

Vuetify Version: 2.3.16
Vue Version: 2.6.11
Browsers: Safari
OS: iOS

Steps to reproduce

1. Scroll down.
2. Scroll back up to the top, overshooting to trigger the overscroll effect.

Expected Behavior

The app bar should be hidden when scrolling down and should reappear after scrolling up.

Actual Behavior

The app bar reappears while scrolling up but is hidden at the completion of the overscroll effect.

Reproduction Link

https://github.com/derat/bugs/blob/main/vuetify/ios-app-bar-hide-on-scroll/index.html

Other comments

I think that #9993 and #10533 discussed similar problems with v-app-bar's hide-on-scroll prop on iOS, but I'm still seeing issues on an iPad Air with Safari 12.1.2 and a simulated iPhone 11 with iOS 13.3 and Safari 13.0.4.

The app bar appears as expected while I'm scrolling up, but it disappears at the termination of Safari's overscroll effect after overshooting the top of the page and remains hidden until I scroll down and back up again. Perhaps relatedly, it also incorrectly reappears when I scroll down to the bottom of the page.

On macOS Safari 14.0, I didn't see the issue with the app bar being hidden when I scroll to the top, but it still unexpectedly unhides when I scroll to the bottom.