Hampton Creek's Just Mayo isn't actually mayonnaise, according to U.S. regulators, because it doesn't actually have eggs in it.
The company behind the vegan spread was issued a warning letter on Aug. 12 by the Food and Drug Administration, citing several purported violations.
Chief among them is the company's allegedly misleading branding of the product.
"The use of the term 'mayo' in the product names and the image of an egg may be misleading to consumers because it may lead them to believe that the products are the standardized food," wrote William Correll, director of the office of compliance for the FDA, in the letter. It was released publicly on Tuesday.
Hampton Creek, whose investors include Peter Thiel, Vinod Khosla and Bill Gates, was also cited for making unqualified health and nutrient claims about the product. The FDA informed the company that it was not allowed to imply that the product was cholesterol-free or that it was heart-healthy.
Hampton Creek declined to comment.
The company has previously addressed some of the criticism around its branding, though.
"We don't call our product just mayonnaise, we call it 'Just Mayo;' that's for a reason," said Josh Tetrick, CEO of Hampton Creek, on CNBC's "Closing Bell" last year.
But that may not fly for much longer.
"The term 'mayo' has long been used and understood as shorthand or slang for mayonnaise," Correll wrote. The FDA gave Hampton Creek 15 working days to respond to the citation.
This isn't the first time that Hampton Creek has encountered an issue with its vegan mayo.
Unilever, the company behind Hellmann's mayonnaise and Best Foods mayonnaise, accused the start-up of false advertising and fraud in late 2014. The food giant ultimately withdrew a lawsuit so that Hampton Creek could address the issue directly with industry groups and regulatory authorities.