It’s a Samsung Galaxy Note 9, with latest updates (Android 10).
I tried disabling all the peripheral devices bluetooth (as mentioned, Remote, Speakers and even phone Bluetooth), but I haven’t tried turning it down from the PPM itself, will check that later.
I remember I was able only once to watch that very same show with Chromecast without stutter, I am not 100% sure but I think it was before last firmware update (so I was on 1.0.27).
Additional note: on my phone the play window of the video I am trying to see has a “cast” icon on it, if I tap on it it lets me chose the device to cast to. The phone says the video is being casted, but nothing happens on the ppm. I tell you just for the sake of completeness, maybe it’s just a bug of the webpage or similar.