I was working on concealing some TV wires, and when I cut through the drywall I noticed this wood behind. I did not have this problem in the bedroom.
How can I avoid hitting wood when cutting through drywall?
People typically use low-cost metal detectors and stud detectors to avoid drilling into or opening holes onto electrical wiring, metal structural members or wooden studs etc.
It's not a stud. Some kind of panel
If a previous owner has somehow attached drywall to what was a completely wood-panelled wall of which you have no knowledge, the only way I'd expect to discover this is by accident when making a hole in the wall.
If the panel is localised, a stud-finder might give you some indications that an area is different from the rest of the wall.
You could buy or rent a DeWalt superman x-ray vision scanner (I may have the model name slightly wrong)