This is not quite fingerprinting, since there's nothing unique about the alleged setup. There's quite a lot required for them to credibly show that the letter

This is not quite fingerprinting, since there's nothing unique about the alleged setup. There's quite a lot required for them to credibly show that the letter could only have been produced on a pc with "Intel HD Graphics 630". I suspect the argument is on the level of "we tried to duplicate it with some random PCs and the one with Intel HD graphics looked most similar". But even if it is true, integrated intel GPUs are in (maybe?) a third of all windows PCs.