My Surface Book 2 developed the yellow blemish issue, just as my SB1 did before. On my SB2 it appeared just after the warranty expired and despite making references to the volume of complaints for the same issue online and the recognition of a product fault they refuse to do anything other than make me pay £500 to repair it.
This issue is enough to make me never want Microsoft hardware, I have owned every generation of Surface product from the start and feel pretty let down by them.