Video lag sound ahead of video and gets progressively worse the longer I let it go

Issue is Xfinity app freezes and buffers, 3 small blinking dots, video comes back but sound is ahead of video. Mouths are moving but no sound for a second or two. The longer I continue to watch the further off it gets. Sound cuts to a commercial while show I was trying to watch keeps playing until it eventually goes to the commercial. Meanwhile the sound has moved onto the second commercial and video is still of first one. I have to exit out of the show then click back on it and it’s fine for a while then starts again. Have multiple TVs and fire sticks. Problem is only with Xfinity app. Direct tv stream works perfectly all day, prime works perfectly all day, Netflix works perfectly all day. Started in February 2026. 7 months later Xfinity can’t fix it. Multiple tickets, multiple chats, multiple escalated tickets to tech support. Prior to February my service worked perfectly on all existing TVs and fire sticks. Even have same problem when watching on my phone at work on a completely different internet and WiFi system. Xfinity can’t fix. Now they are sending a tech out and threatening to charge me if it’s in my equipment. I only have their modem. All service is fed thru WiFi. And like I said worked perfectly for years till February and now they can’t fix. I’m at my patience end.