Also I can confirm that HEVC + alpha channel HLS stream works as expected in SpriteKit as SKVideoNode despite not working in SceneKit as SCNMaterial

One dirty workaround is to use a SKVideoNode embedded in a SKScene as a SCNMaterial. However this is not a suitable solution as it loads the CPU with additional 30-40% on iPhone 11 Pro making my ARKit application well above 100% CPU while the AVPlayer SCNMaterial was very CPU efficient...

Reproduced on 15.2.1