Safari 16.4 now supports OffscreenCanvas, but only with a 2D rendering context, not WebGL/WebGL2. This causes issues because the engine assumes that if we have access to an OffscreenCanvas, that we can get a WebGL context out of it. The HTML gradient renderer uses an OffscreenCanvas with a WebGL context to create the gradients it needs, so apps that use this gradient will crash in Safari 16.4.