A recent regression in iOS 15.4 causes https://www.colorizephoto.com/ to stop working, affecting many site users. Disabling WebGL via Metal restores functionality to the site.
Ensure 'WebGL via Metal' enabled: Settings App -> Safari -> Advanced -> Experimental Features -> Turn on 'WebGL via Metal'
In Safari, go to https://www.colorizephoto.com/converter
Try painting on Clint Eastwood's face
The black/white photo should have skin color where you paint
Nothing happens - no coloring of the black/white photo
Try again after turning off 'WebGL via Metal' to see the correct behavior
Still repros on iOS. Unclear if bug 240790 is the root cause