How to fix gaps between seamless objects in Three.js?

Question

I am trying to achieve seamless objects next to each other in Three.JS which currently works fine on most devices / browsers but in some cases i'm experiencing difficulties. For example while using MacOS with the latest version of Google Chrome (and also Safari) the objects render with pixelated gaps in between that should not be there.

Bug occurs with all 3D Objects, GLTF models (left) and BoxGeometry (right):

While using the same Mac device but using Firefox everything renders as expected:

Sizes are exactly (1, 1, 1) and should fit exactly next to each other. I've also tried to scale it up to (1.05, 1.05, 1.05) but this didn't fix the problem, in fact it only got worse as applying scaling results in Z-fighting when textures are enabled.

I'm currently using R137 of Three.JS and made sure my application correctly applies window.devicePixelRatio so that should not be the problem either - is there any other renderer setting that i'm forgetting which could help resolve this rendering issue?

The behaviour for Android and Windows devices also works correctly. The used Android device has a devicePixelRatio greater than 2 and everything looks smooth there. I doubt it's a problem with my Mac GPU as it renders correctly with Firefox; is this a bug of the browser maybe, and is there something we can do about it ourselves?

Hopefully this is not a duplicate, i couldn't find any solutions/answers to this.

EDIT:

I've found out that EffectComposer (for FXAA) are causing these problems for Google Chrome / Safari on Mac devices. Which is weird because it works completely fine on all other devices. I'm currently still looking for a way to fix this. If anyone had problems in the past with EffectComposer for Mac and managed to fix them please share your solution with us. When replacing FXAA shader with for example Sepia shader the same bugs occur, it doesn't seem to matter which shaders are being passed, anything pass from EffectComposer causes this.

I've made a fiddle: https://jsfiddle.net/ilanbentley/g3yxdvmh/3/ Note how the right side (EffectComposer) has buggy edges while the left side (Renderer) looks good (for Mac).

Somehow the code below is responsible for this buggy behaviour:

    const renderPass = new RenderPass( scene, camera );
    fxaaPass = new ShaderPass( FXAAShader );
    composer2 = new EffectComposer( renderer );
    composer2.addPass( renderPass );
    composer2.addPass( fxaaPass );