We've received reports of rendering issue with materials, including translucent and dashed line materials, in CesiumJS on iOS devices using WebGL via Metal (https://github.com/CesiumGS/cesium/issues/9827
We were hoping this would have been fixed with the latest WebGL related fixes that went out with Safari 15.5, but that doesn't appear to be the case.
Disabling order independent translucent appears to remedy the issue, so we're working on narrowing the issue down to a specific extension, though we believe it may be related to EXT_color_buffer_float. In the meantime, have others run into a similar issue? If not we can file a new report with Webkit.