iOS 15.4 shadows pixelated - maybe precision issues?

Hi there
in iOS14 the html5 export was pretty consistent in iOS and when running in Chrome.
but now with iOS15 there is an issue with real-time shadows.

The shadows gets all pixelated and very low resolution in iOS safari.
A guess will be shaders precision in Kha :
https://github.com/Kode/Kha/search?q=DEPTH_COMPONENT

is there a switch to activate higher precision in webGL2 :
GL.DEPTH_COMPONENT24

I tried editing some Kha files but get the following:
WebGLImage.hx:207: characters 69-86 : Class has no field DEPTH_COMPONENT24
while the '24 depth' should be accessible in the webGL2 context.

Start by reviewing the Kha references to DEPTH_COMPONENT and WebGLImage.hx around line 207, then compare the WebGL2 depth behavior in iOS Safari with Chrome and iOS 14. Done means real-time shadows render without pixelation or low resolution in the iOS 15.4 HTML5 export.

Written by the indexing model from the issue text.