I recall my colleague facing a similar problem. It was related to general usage of the image for display. She then used a third party opensource to display the image that optimized it.
Believe it was FFImageLoading -
GitHub - luberda-molinet/FFImageLoading: Image loading, caching & transforming library for Xamarin and Windows[
^]
You would need to scale down your image. Something like:
From:
<Image Source="mypic.png" />
To:
<ffimageloading:CachedImage Source="mypic.png" BitmapOptimizations = true, DownsampleToViewSize = true/>
Believe there would be difference in how Android10 & Android11 is working behind the scenes for this rendering leading to issue in one only.
PS:
1. As Dave suggested, also check for any memory leaks or holding on to not needed resources that could be leading to issue.
2. Make sure you have all the components latest & compatible that are part of your project