The pnetter who has info on Kevlar
darkening and laminate strength is Eric Nyre.
I have googled around on Kevlar qualities quite a bit, and I have not seen any consistent concern about it having special UV susceptibility. I think the boat makers must not be TOO concerned either, because they could easily put a thin layer of UV resistant paint over the inside of canoes where the Kevlar is exposed.
We know that epoxy is quite susceptible to UV damage, but my Bluewater came with the inside laminate fully exposed. Do the makers know something we don’t know?