iOS Webview showing layers with darkened or bolded areas on layers

Hello - I have a native iOS app using a webview to view layers in 3D. We notice that if you add a couple layers and start zooming or tilting the view, portions of the layers turn black or the pixels become bolder. As you add more layers to the view, the issue is exacerbated and more darkened areas occur.

We've tested this on our native Android app and on a PC web browser (chrome) and do not experience the issue. It seems to be specific to our native iOS app using webview. We can also recreate it on iOS with safari web browser.

We are wired up with Cesium 1.52, OL-Cesium 2.5

Screenshots provided are from a 3rd Generation iPad Pro, iOS 12.1.4
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I'd welcome your feedback or ideas,

I wonder if this is related to this:

What type of imagery layers are these? How big are they? Are you able to recreate this with any of the imagery layer Sandcastle examples:

Or if not, is there a minimal Sandcastle you can put together that has this issue?

Hello, I don't believe it is related to issue 6477.

In most of the cases where we see issues, we are using transparent png layers (8bit png).

My developer has a sandcastle setup to recreate the issue. We've added some of our layers to the map. I've indicated some of the areas with red outlines. We also see the issue with the bing label layer (with transparent background)


Thanks for the Sandcastle! I am indeed able to recreate this now on an iPad. I opened a bug report here to track this:

This bug has just been fixed! It’ll be available in the next Cesium release (1.57) on May 1st.

More details on the fix in this PR: