I am able to continue feeding necrocorns to the leviathans beyond my stated cap. Currently, I am at 696 / 405, and my trade ratios still seem to be increasing with more feeding despite being over the cap. I have 80 markers and 15 runs of black sky. I believe the 405 is calculated from the markers alone (5 + 5*markers per the wiki), so it seems the cap does not account for the bonus from black sky. The wiki says black sky increase is +0.5 per marker, capped at 10 with diminishing returns. Not sure where the diminishing returns kick in, but if I haven't hit them yet I think my "real" cap will be at around 1000, not sure if I will stop being able to feed more then or if I will be able to continue feeding, just won't improve my trade ratios? I am on mobile, not sure if this is a bug specific to mobile or if it would happen in browser too, I haven't ever exported my save over.