Members of the platform have expressed outrage following a change that caused listings displaying inaccurate size information.
The second-hand shopping app has revised its measurement guidelines for women's and children's clothes failing to inform all shoppers about the modification.
Many shoppers and sellers are posting online saying Vinted listings now show a different size category versus the original listing as a result of the reclassification.
Vinted explained the updated approach better aligns with comparable marketplaces.
The platform has recommended to review their products and adjust the sizing manually where appropriate, causing user dissatisfaction.
Earlier, the sizes had both a single numeric size and a letter, like S/8 or M/10.
The updated approach includes an alphabetical indicator and numerical range like S/UK 8-10.
With some products, the size labels have been reassigned - for example a size L was formerly size 12 but now shows as UK 16-18.
A fashion influencer, who produces content about larger sizing, stated the update "complicates both purchasing and selling".
"Rarely do manufacturers list XL as sizes 20-22," the way the service now categorizes.
Another user, located in Scotland, stated items she posted with size 14 tags were showing in the marketplace as measurements 20-22.
"If buyers measuring 20-22 acquire them they will likely be quite upset," she explained.
Another shopper, located in England, stated she felt frustrated by the change as she had to manually change the measurements for "each individual item".
"This situation is especially annoying, since I have chronic health issues and Vinted sales have been crucial after experiencing income reduction," she said.
The service features exceeding 100 million users, including 18 million in the UK.
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: earlier, the platform withdrew an update concerning shipment methods after backlash from users.