S5E1, why was the meth switched out?
So Lalo's on the scene and pretty quickly finds parts of Fring's operation that don't add up, and the first bit of compelling evidence he finds is the meth Nacho picks up from the chicken farm being mixed in with other meth, which he verifies by inspecting it thoroughly and taking a few quick bumps
We know from earlier that Gus has finally started mixing cartel batches with locally sourced meth after secretly sabotaging their smuggling operation and having Gale test some samples, so it's fairly clear WHERE the meth is from, but WHY is it there?
Presumably Gus is positioning himself so he can make money free of cartel supply without seeming too suspicious, but it wouldn't make any sense for Bolsa to hide supply chain issues that reflect poorly on the Salamancas while also making less cash, and in any case that can't be his excuse for this particular batch of meth being switched because when he's asked to explain himself, he lies to Bolsa and Lalo that the missing Salamanca meth was stolen by Werner, and Gus' admission says that the meth was inferior in quality, which seems to be verified by Lalo's nose
So what's the real reason he gave them inferior meth? Given the elaborate lie he told, it's clearly part of his wider plans against the cartel, but how does giving the Salamancas inferior meth, which goes to dealers and gets mixed in with cartel meth anyways, further his agenda?