My Macbook Pro 2017 (15 inches, 2.9 I7, 16gb) began to have these video issues, small glitches with horizontal lines. It had happened before, but after the upgrade to Catalina they seem to have become more frequent.
They happen when I unplug the charger and start using the battery. I searched online and found that if I turn off the "Automatic Graphic Switching" option the problem stops happening but the battery consumption increases.
The video below shows the glitch and how it stops when I turn off Automatic Graphic Switching
I imagine the problem is related to the Intel HD Graphics 630 or the switch between it and the Radeon Pro 560.
My computer is all up to date (Catalina 10.15). Is there anything I can do? I'm worried if it's something that gets worse. Thank you, Daniel