I am trying to watch a file that is hosted through the real debrid network.bi can watch the video on my phone but the option to cast to my Chromecast is gone. I remember it working in the past but it doesn't anymore. I can cast YouTube and Netflix so it doesn't seem to be the phone or the Chromecast at fault here.
This is likely an anti piracy measure that Google have started taking for their devices. Google make the Chrome Web browser, android and the chrome cast. It gives them leverage to do this quite easily.
In recent times they have been blocking the ability to cast from lots of websites like real debrid that are flagged for piracy. You will have to get creative if you want to make this work.