Playground crash in iOS Safari with Gutenberg PR testing in /wp-admin/

[brandonpayton]

On an iPhone 16 Pro with iOS 26.2, opening the following link in iOS Safari leads to a Safari error with no Playground UI loaded. To reproduce, the link needs to load /wp-admin/, and you have to wait for a moment for the page to be forcibly reloaded.

https://playground.wordpress.net/?gutenberg-pr=74598&url=%2Fwp-admin%2F

The result:

Here is a video:

ScreenRecording_01-14-2026.14-08-21_1.mov

It does not seem to matter what Gutenberg PR is used. @ellatrix first reported this issue with the following Playground URL:

https://playground.wordpress.net/?gutenberg-pr=74596#%7B%22landingPage%22:%22/wp-admin%22,%22login%22:true,%22features%22:%7B%22networking%22:true%7D,%22steps%22:%5B%5D%7D

[brandonpayton]

I connected my iPhone to the macOS Safari dev tools and looked at what was happening. There were no console error messages or network requests that seem to be related or causative.

I tried recording events on the Timeline tab to look for clues but didn't find anything. The Timeline seemed to struggle with finishing collecting data to display it. Maybe it is related to the page load going away and failing over to a Safari "problem repeatedly occurred" error page.

Google suggests:

The "A problem repeatedly occurred" error in Safari, especially when related to WebAssembly (WASM),
often indicates that the webpage is using a significant amount of system resources (like memory) and the browser or operating system is terminating it

But unfortunately, the contents of the Safari devtools Timeline Memory tab seemed inconsistent during my test runs.