When I launch this test in Chrome or Firefox the panning background material smears as it scrolls. There’s no lighting in the scene, the sky material is emissive - thought this might have something to do with it but I’ve tried it as a normal material lit with a spot light and the same thing happens… Plese ignore mad pixelation.
I have reproduced your issue and logged it, you can track it here:
Please be aware that this issue may not be prioritized or fixed soon.
However, this issue did not occur for me if the image is a power of two in size ( 256, 512, 1024, 2048 pixels) these sizes are the standard in the engine.
