I'm not a chemist, but from my rudimentary understanding, i'd guess that weaker acids are preferrable, if the strength matters at all. My reasoning is that when you have both an acid and a base in the same solution, you are creating a buffer system, and that will trap *some* of the alkaloids in solution - and i'd assume a stronger acid traps more. I could be wrong at every step here, of course ...
If vinegar does lead to lower yields compared to other acids (which would need either a pretty rigorous experiment where all other variables are identical, or one of the chem flask heads giving a reasonable explanation, for me to believe), my guess would be that it's because it "bonds" too strongly to the DMT, not too weakly, and therefore traps more DMT in the buffer.
Another, perhaps more likely explanation, is that people simply used too much vinegar, then needed too much lye, and thereby increased the amount of DMT trapped in the buffer.
Remember that acid molecule + DMT freebase molecule => DMT ion + ion of the acid, and both should be floating pretty freely in the water. If they do form any bonds, we actually need them to break up when we add the base, because we want the DMT as freebase, which will migrate into the non-polar solvent.
There is at least one A/B tek on the nexus that doesn't add any acid in the A phase (because there is plenty of tannic acid in the bark):
https://www.dmt-nexus.me...aspx?g=posts&t=83510ACY was maybe a bit over the top with safety considerations there, but keep reading. I have tried this tek, and i had 1.2% yield in my first pull - better than with any other tek i tried with the same bark, and about 80% of total yield i usually achieved with that bark - using STB or A/B with acetic or citric acid.