When I look at the first picture, it looks like the Bayer filter is showing up in the photo. I do a lot of astrophotography and these lines show up in color cameras that of course have a Bayer filter. The software I use has a “debayer” tool, but it is specifically a software for Astro pics. I don’t know if Lightroom has a tool to fix, but Topaz Photo can remove the noise and smooth out the matrix you are seeing.
Another thought. There might be specific zoom levels that show the Bayer filter more than others. If you crop in more, do the lines go away? It might be the resolution of your monitor doing weird things when you crop in tighter.
Those are my guesses. I’m not an expert in the technology of sensors. I’m sure someone more knowledgeable will come along with a better answer for you.