WebGL2's RenderTime is much higher than WebGL1's on IOS

Playground is here(I download it and run server locally so that I can disable WebGL2): Babylon.js Playground
Device:iPhoneX
OS: IOS 15.4.1
Browser: Safari
RenderTime: 800ms(WebGL2) | 400ms(WebGL1)

ping @sebavan

This is so weird !!! I can repro on my phone and knowing both render the exact same now, this does not make any senseā€¦ This is unfortunately not something we control, could you log a bug for webkit ?