Qt WebAssembly not working on iOS (Regression)

Qt Web Assembly Applications fail to load on iOS devices. Interestingly, this is specific to the platform, not the Browser. The same application fails to load on Safari and Chrome on iOS, but works flawlessly on Chrome on any other Platform.

I uploaded a qmake hello world app built with 5.15.0 WASM here:
https://pwuertz.github.io/iosfail/QtWasmTest2.html

On iOS devices, the application exits at startup with the error message:

Application exit (TypeError: undefined is not an object (evaluating 'handle[name]'))

I tried the reference 5.15.0 distribution with the suggested emscripten version 1.39.8, as well as updating emscripten and compiling Qt Wasm myself, to no effect.