I have had this LG SmartTV for 2 months now and it constantly buffers ONLY with the Xfinity App. I can watch Netflix and Peacock with NO streaming issues. I also have the Roku in another room and it streams Xfinity just fine and it is no closer to the wifi infact is has more walls between the router and the TV. I have called several times and they always tell me there is an issue with streaming and it should be fixed shortly. It's been 2 months - I believe there is an issue with your app and needs updated. I tried to delete the app and reinstall per my LG customer support but it didn't work and the last update is 4/2020.
We have had the app for at least 6 months and have an LG tv. It is an AWFUL experience. No exaggeration - every single time we use the app on TV, it freezes. I have contacted Xfinity via chat about 5 times in the last 6 weeks. I've even asked for a regional contact person to share my feedback with, because it doesn't seem to be getting better. We have tried everything.