Never had long term luck trying to isolate only one streaming app to work on a VPN, it is hard to find out all the servers they use and as it changes constantly it requires too much management. And even if all the configuration is good eventually the IP address gets leaked and it stops working.
Easiest way to manage that is to have an extra streaming device dedicated for VPN usage and then configure the VPN for the whole device.
Here I have 2 Google Chromecast TVs, one running local w/o VPN, the other connected to USA through a VPN. There is an extra cost at the beginning as you need to buy an additional device but it is “set and forget”, does not stop working suddenly and I easily saved more in time than I had paid for the extra device.