One big difference - the kennufs-hybrid-v13 recipe should have a lower glycemic index than Soylent. Soylent is made with a lot of maltodextrin, which is very fast glucose. The kennufs recipe has a lot of brown sugar and masa, both of which are lower GI. Sugar is half glucose, half fructose, so it has a GI of 65, compared to straight glucose’s 100.
Meanwhile, Schmoylent uses maltodextrin, but it has twice as much oat flour as maltodextrin. Retail Soylent, on the other hand, has more maltodextrin than oat flour (biggest ingredient must be listed first.) Again, Soylent should have a significantly higher GI than Schmoylent.
Is your lethargy setting in about two hours after consuming? If so, the lethargy you’re describing sounds consistent with having your blood sugar dip after having your insulin rise very high because of a meal that, for your system, is relatively high in simple carbs. If it’s much quicker than that, then maybe this isn’t the culprit.