Members of the platform have expressed outrage due to a modification that led to items being listed as the wrong size.
The popular resale platform has updated its size classifications for women's and children's clothes failing to inform all shoppers about the modification.
Many shoppers and sellers have taken to social media claiming that product pages now present a modified sizing category versus the original listing because of the remapping.
Vinted explained the new system was more in line with comparable marketplaces.
It has advised users to examine their items and update the measurements by hand when needed, resulting in member annoyance.
Previously, the sizes had both numerical and alphabetical indicators, for instance S/8 or M/10.
The new system has a letter with a size spectrum such as S/UK 8-10.
In some cases, the size labels have been reassigned - such as a large size was formerly size 12 but now shows as UK 16-18.
One content creator, who makes TikTok content about plus-size fashion, said the change "makes both selling and buying harder".
"Rarely do manufacturers list XL as sizes 20-22," as the platform currently indicates.
Another user, based in Glasgow, said garments she listed on Vinted with size 14 labels were showing in the marketplace as measurements 20-22.
"Should someone sized 20-22 purchase these they may become frustrated," she explained.
Charlotte Lunn, located in England, said she had been left angered due to the update requiring manual adjustment the measurements for "each individual item".
"This situation is especially annoying, since I have chronic health issues and platform income has been essential for me since losing part of my income," she said.
The platform boasts over 100 million shoppers, with 18 million British users.
It has become a favored option compared to resale services such as eBay and Depop.
This represents another occasion when a surprising modification on the platform has faced criticism: last year, the service retracted a modification concerning shipment methods due to shopper criticism.