Their support site literally says “when you don’t have an internet connection” so if it’s working the way you describe then it’s not working as designed.
I use Linux but the only issues I have are 1) lower quality, since the best quality is usually restricted to Chrome and Edge on Windows and Max, and 2) no downloads.
Their help page says you can download to watch where you don’t have an internet connection. So if there is some DRM BS then that’s going directly against what their help page indicates.
I love openSUSE and think it’s one of the few distros that has a pretty good implementation for every DE/WM. GNOME, KDE, Xfce, lxqt, enlightenment, mate, sway, etc… are all a solid experience on openSUSE.
That said, I have never found a distro with a good Cinnamon experience other than Linux Mint. Probably in part due to cinnamon being developed by mint, but regardless, if you want to use cinnamon, mint is your best option.