Shoppers are voicing their frustration following a change that caused items being listed as the wrong size.
This online marketplace has altered its measurement guidelines for women's and children's clothes but did not contact all users about the change.
Countless users and merchants are posting online stating that platform listings now display a different size category than originally posted because of the remapping.
The company said the updated approach better aligns with similar services.
It has advised users to examine their items and manually change the size if necessary, resulting in member annoyance.
Previously, the sizes had both numerical and alphabetical indicators, such as S/8 or M/10.
The new system has a letter with a size spectrum such as S/UK 8-10.
With some products, the measurements have been reclassified - like an L measurement was previously a 12 but is now a UK 16-18.
Frankie Bridger, who makes TikTok content about plus-size fashion, explained the modification "makes transactions more difficult".
"Not many brands say XL is a 20-22," which is what Vinted now does.
Stephanie Gallen, located in Scotland, explained products she uploaded on Vinted with size 14 labels were showing in the marketplace as measurements 20-22.
"If anyone [who is] size 20-22 buys them they will likely be quite upset," she explained.
Another shopper, located in England, explained she became annoyed due to the update requiring manual adjustment the sizing for "all her products".
"This situation is especially annoying, because of my ongoing medical condition and selling on Vinted has been paramount for me since losing part of my income," she said.
The service features exceeding 100 million members, including 18 million in the UK.
It has emerged as a preferred choice versus similar marketplaces including eBay and Depop.
This represents another occasion that an unexpected update within the service has received backlash: last year, Vinted reversed a change concerning shipment methods after backlash from users.
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