End Portals, when viewed behind either water or glass, will flash violently. I have tested the Xbox One Beta and Nintendo Switch versions, which neither have the bug. I am not currently able to get the video onto the laptop since it isn't mine, my phone wouldn't co-operate with the site very well, so I do hope that this twitter link of the bug on video will work. https://twitter.com/SourGummyes/status/1316438254250594305?s=20