I would say fried, cooked, whatever overheated or damaged GPU, at least that's the only way I was able to see such Graphic problems.
If you didn't mess with LFS or try to download the default and test, it's very likely a GPU problem or a Driver problem, but I would be surprised about the drivers after so many years of their development, I'm used to different graphic problems with drivers.
Is it doing right after start of LFS? or after 1 hour when the GPU gets hot?
etc. I would suggest inspect GPU, do a series of graphic tests, benchmarks, and monitor the temperature of Graphic card. Try to use latest drivers available.