Multisampling on newer iOS depth/stencil issue

Description of the bug

The scene depth/stencil rendering is broken on iOS devices version 15.4+ (supporting WebGL 2.0) when multisampling is enabled. This works as intended on the desktop and also on older iOS devices, where WebGL2 is not supported. When the multisampling property is removed, all works even on 15.4+ iOS versions. Tested on several iOS devices.

This video shows what is happening:

https://user-images.githubusercontent.com/24633729/192964722-5b2d641b-ef3c-4f1a-be68-369fd5369d62.mov

To Reproduce

Everything is standard code for working with PP.

const renderer = new THREE.WebGLRenderer({ 
    powerPreference: "high-performance",
    antialias: false,
    stencil: false,
    depth: false
});
const maxSamples = renderer.capabilities.maxSamples;
const composer = new EffectComposer(renderer, { multisampling: Math.min(4, maxSamples) });

const noiseEffect = new NoiseEffect({premultiply: true})

const effectsPass = new EffectPass(
    camera,
    noiseEffect
);

composer.addPass(new RenderPass(scene, camera));
composer.addPass(effectsPass);

Expected behavior

This video shows the expected behaviour. It is the same footage as the previous one, but without the issue / multisampling set to 0:

https://user-images.githubusercontent.com/24633729/192964592-f0aec077-0316-4615-869a-cc7512a98651.mov

Library versions used

• Three: 0.144.0
• Post Processing: 6.28.7

Mobile

• Device: iPhone SE 2020
• OS: iOS 15.4+
• Browser: Safari / Chrome

[otrubakarel]

I can also confirm that this bug is no longer present on iOS v15.7

[vanruesc]

I was able to reproduce the issue on an iPhone 13 with iOS v15.4 via browserstack but I did not see the bug on iOS v15.5. So it looks like this was fixed in v15.5.

I used the following Sandboxes for testing:

1. MSAA buffer + copy to screen // https://e3z8n2.csb.app/
2. MSAA buffer + render to screen with effects // https://8rcqnu.csb.app/