Bug 306598 – REGRESSION: Scrolling during low frame rate (LFR) leads to unresponsive touch events on iOS 26

• Status: RESOLVED
• Resolution: FIXED
• Component: WebGL

Created attachment 478199 [details]
Screen recording demonstrating touch unresponsiveness triggered by rapid vertical scrolling on iOS 26.

A critical issue has been identified on iOS 26 where frequent and rapid scrolling/swiping gestures lead to a complete loss of touch responsiveness. Once the issue is triggered, the page no longer responds to any scrolling or tapping events.

URL:
https://qfqf456456.github.io/qfqf456456-IOS26TouchDemo/

Steps to Reproduce:
1. Open the provided URL on a device running iOS 26.
2. Perform rapid and frequent swiping/scrolling gestures vertically on the page.
3. Continue the scrolling interaction for a few seconds.

OS Version: iOS 26.2

Additional Context:
This behavior is consistently reproducible on the provided demo page under high-frequency touch interaction.

[Radar WebKit Bug Importer]

<rdar://problem/169279665>

[Simon Fraser (smfr)]

I can reproduce poor scrolling on the testcase. The test page uses canvas to render, so it's not really scrolling.

[Simon Fraser (smfr)]

It's actually WebGL.

Pull request: https://github.com/WebKit/WebKit/pull/59255

[EWS]

Committed 308237@main (a1a65ba028eb): <https://commits.webkit.org/308237@main>

Reviewed commits have been landed. Closing PR #59255 and removing active labels.