Describe the bug

When scrolling up to items of unknown height in iOS Safari, the grid appears to glitch briefly as items are mounted.

This does NOT happen:

1. When scrolling down
2. On desktop MacOS
3. When items have known height, either from being mounted previously or given explicit height

Reproduction

https://codesandbox.io/s/optimistic-blackwell-5pnlx7

To Reproduce
Steps to reproduce the behavior:

1. Visit https://5pnlx7.csb.app on iOS device through the Safari app
2. Scroll up
3. Observe there is some glitching

Expected behavior

No item shift/glitching upon scrolling up.

Screenshots

Additional context

This glitching is also visible, although much, much less obvious (due to small size variance and white bg) on https://virtuoso.dev/prepend-items with iOS Safari.

I am using this great library for the new FOSS project I've been working on, Voyager, a Lemmy client. I know $100 one-time isn't much, but it's a good amount of the sponsorship money I've received so far and as I continue to receive github sponsor money from Voyager I plan on forwarding a portion to you because this project makes Voyager possible so thank you!