Aardenburg has some tests of Hahnemuhle Bamboo with both HP Vivera and different Epson inksets. It's worth taking a look at these. I looked at a couple of the Epson inkset tests and they showed a significant deterioration in the paper white patch so I wonder if there is residual lignin in the paper as this would cause yellowing. The HP inkset seemed to be much more stable but the paper white patch didn't show as much deterioration which is curious to me.
Your comment caused me to go back and review some of the Bamboo light fade testing results again. My take on these test results is that the whitepoint shifting in the Aardenburg tests was not due to lignin discoloration. The light bleaching effect caused a a shift towards a cooler paper white value compared to the initially very warm white point value in this paper. These test results are an indication that Hahnemuhle has done a pretty good job of removing any lignin which if present would have promoted an increase in yellowing not less.
Any number of possible chemical reactions can account for the light bleaching of the Bamboo paper, but one industry practice is to add a variable amount of "leveling dye" to the paper pulp in order to maintain whitepoint consistency batch to batch. Bamboo normally measures a LAB b* value very close to +4 (ISO 3655-2009 M0 defined measurement) which is noticeably more yellow than most fine art media, including OBA-free media. It might be harder to control that creamy warm-white value precisely in paper production without resorting to a dye leveling method during paper production. In any case, the Bamboo paper color bleaching in the Aardenburg light fade tests, IMHO, is not too serious, nor is it going in the direction of yellow discoloration, so I would not be too concerned. It isn't best-in-class whitepoint stability performance, for sure, but it's also not nearly as serious a discoloration issue as we have seen in other media, for example, Epson Exhibition Fiber paper.