So it's not a lawsuit (yet), it's a complaint to the state attorney general of Washington accusing Starbucks of unfriendly consumer practices related to their gift cards, in part because they can recognize unspent gift cards as revenue, and also because it's instant cashflow for them even if the accounting revenue lags behind. The need to come up with a calculation for how much deferred revenue to recognize can be abused by execs to nudge the revenue higher (and with no additional costs associated with it, profit as well) and thereby improve stock price and trigger bonuses and whatnot.
The actual complaint reads as a bit of pearl-clutching ("involuntary subscription" because customers don't want to leave a balance OR talk to a real human at their local Starbucks!) , but on a the "death by a thousand cuts" model, yeah, I suppose Starbucks is being kinda dickish. The app doesn't give you as many rewards if you pay with CC, buries the other payment options a couple of layers deep in a menu, doesn't let you reload gift cards in increments equal to a purchase, doesn't let you split payment methods, and sets a high default reload so (on iOS at least) it isn't immediately visible that you even could scroll up to reload in smaller amounts.
It's sort of garden variety asshole app design meant to soft-lock customers in, but it's not really fraud in any meaningful way if someone is motivated. You add money, you get bitter overpriced coffee that your partner really likes for some reason. I prefer CHEAP, ACIDIC coffee because I did the pourover too fast on mediocre store-bought grounds that are too fine, LOL. Still, maybe worth a public scolding or some fines to get them to modify it so people can save a few bucks without diving into the finer nuances of their coffee app.