A new legal battle has emerged against Costco, as the retail giant faces allegations of misleading consumers with its Kirkland Signature brand tequila. The lawsuit, filed in Florida at the end of October, claims that the tequila, which is promoted as being crafted from “100%” blue Weber agave, is, in fact, adulterated with alcohol from non-agave sources.

According to the lawsuit, the tequila in question may not even qualify as a “mixto” tequila. Typically, a mixto tequila consists of at least 51% agave, with the remainder made up of other sugar sources. The complaint suggests that Costco’s Kirkland Signature product fails to meet the strict standards set by Mexico’s tequila regulatory council, which could mean it doesn’t technically qualify as tequila.

The plaintiffs in the case, hailing from Florida and potentially other regions, argue that they were misled by Costco’s labeling. They claim that had they been aware of the true composition of the tequila, they might have chosen not to purchase it, or at the very least, would have expected to pay a lower price.

This lawsuit follows a pattern of scrutiny over Costco’s product offerings, including a recent recall involving nearly one million bottles of wine sold at the retailer, highlighting ongoing concerns about product integrity and consumer safety.

At Costco’s official website, some of the tequilas named in the lawsuit (which include the entire Kirkland Signature line of tequilas) are advertised with language on the label reading “100% de Agave,” “100% Blue Weber Agave” or “100% Blue Agave.” Only tequilas made in Mexico with 100% blue weber agave (and bottled “at the source”) can be marketed as such, according to the Consejo Regulador del Tequila (CRT), Mexico’s tequila regulatory council.

In the complaint, the plaintiff alleges that she commissioned a lab to test the concentration of agave-derived ethanol in Kirkland Signature tequila. That testing, according to the complaint, turned up an “isotope signature” that suggests a significant amount of the spirit was distilled using sugarcane or corn.

The plaintiff is seeking damages and attorneys’ fees, as well as “any other just and proper relief” under the Florida Deceptive and Unfair Trade Practices Act.

A representative for Costco did not immediately respond to questions concerning the complaint on Monday. The Seattle Times and USA Today, both of which reviewed the complaint last week, were also unable to get a response from Costco on the matter.

In recent years, popular tequila brands other than Kirkland Signature have come under scrutiny for the amount of blue Weber agave used in production, including Casamigos, Don Julio and 818, according to Drinks International and Mezcalistas.

Experts say these accusations have become more common in the tequila industry, as the production of legitimate tequila can be a lengthy process: Only blue agave plants from specific regions in Mexico can be used in the production, and these plants can take up to 10 years or more to fully mature.

Agave farmers have since battled with supply and demand, as well as problems created by larger tequila producers who bought up land and planted large agave crops, hoping to help ease pricing but upsetting the delicate balance that smaller suppliers have worked under for decades. Some producers, too, had taken to adulterating their product with sugars derived from non-agave sources, Remberto Galván Cabrera, the spokesperson for the Mexican Agave Council, told Mezcalistas earlier this year.

“The truth is complicated, and it’s sad for us,” Cabrera said.