Pixelation/Tiling of TV picture following “network enhancements”

Two days ago Comcast/Xfinity notified myself and my neighbors they were completing "network enhancements" in our atea and so our Xfinity services would be interrupted for most of the working day.

After service was restored (and I got the all clear notification from Xfinity), I noticed all TV pictures now suffers from heavy pixelation/tiling when watching any channel live. It's awful and impacts all channels. I never had these issues before in the 6 years I’ve lived here and now my TV programming is barely watchable. Tried box reboots, signal refreshes, etc. to no avail. Signal strength shows “Good” on my DVR menu. Nothing has changed inside my house. What did they do during the “network enhancements” that impacted my TV picture like this, and how do I get it fixed? Please help!