Youtube Vanced working with Chromecast (kind of?)

Hello everyone,
I am quite new to the /e/OS, but as far as I could read through the forum the native chromecast option shouldn’t work.

But I am a bit confused that I can use it with the Youtube Vanced App and the Netflix App.
I can cast the Video to my 2018 LG TV and my XBOX One.

On the other hand I can’t use the Prime App with any device. It only shows my Onkyo receiver (Audio Chromecast built-in) but I am not able to connect.
So is /e/OS working with Chromecast or is this a coincident?

I use a Fairphone 3+ with the newest e/OS/.

Youtube Vanced
-> works: LG TV SJ8509, XBOX One
->worked twice: Chromecast Ultra

->works: LG TV SJ8509, XBOX One
->doesn’t work: Chromecast Ultra

Amazon Prime
-> shows device but unable to to play: Onkyo receiver
-> doesn’t work: any device