Members of the platform have expressed outrage due to a modification that led to products showing incorrect sizing.
This online marketplace has updated its size classifications for women's and children's clothes without notifying all users about the change.
Numerous buyers and vendors have taken to social media claiming that product pages now present 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 review their products and adjust the sizing manually where appropriate, resulting in member annoyance.
Before the change, the sizing featured numerical and alphabetical indicators, like S/8 or M/10.
The new system has an alphabetical indicator and numerical range such as S/UK 8-10.
With some products, the size labels have been reassigned - like an L measurement used to be a 12 but is now a UK 16-18.
A fashion influencer, who creates plus-size fashion videos, stated the update "complicates both purchasing and selling".
"Not many brands say XL is a 20-22," as the platform currently indicates.
A different member, based in Glasgow, explained products she uploaded with size 14 tags were displaying on the service as size 20–22.
"If anyone [who is] size 20-22 buys them they may become frustrated," she explained.
Another shopper, based in Derby, said she had been left angered by the change as she had to manually change the sizing for "all her products".
"For me this is particularly frustrating, as I'm chronically ill and Vinted sales have been crucial after experiencing income reduction," she said.
The service features exceeding 100 million users, with 18 million British users.
It has emerged as a preferred choice versus similar marketplaces including eBay and Depop.
This represents another occasion that an unexpected update on the platform has faced criticism: earlier, Vinted reversed a change to its shipping options due to shopper criticism.
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