Shoppers are voicing their frustration following a change that caused items being listed as the wrong size.
This online marketplace has updated its size classifications for female and kids' apparel but did not contact all shoppers about the modification.
Many shoppers and sellers are expressing on platforms saying Vinted listings now show a modified sizing category than originally posted due to the recalibration.
Vinted explained the revised method more closely matches other platforms.
It has advised users to check their listings and manually change the size where appropriate, which has left users frustrated.
Before the change, the measurements included one number and one letter, such as S/8 or M/10.
The revised method features an alphabetical indicator and numerical range such as S/UK 8-10.
With some products, the size labels have been reassigned - such as a large size used to be a 12 but currently displays as UK 16-18.
One content creator, who produces content about larger sizing, stated the update "complicates both purchasing and selling".
"Rarely do manufacturers list XL as sizes 20-22," which is what Vinted now does.
Stephanie Gallen, located in Scotland, said garments she listed featuring size 14 markings were showing in the marketplace as measurements 20-22.
"Should someone sized 20-22 purchase these they're going to be very disappointed," she said.
A different user, based in Derby, explained she became annoyed because the modification necessitated personal updates the sizing for "all her products".
"For me this is particularly frustrating, because of my ongoing medical condition and platform income has been essential following partial earnings loss," she explained.
The app has more than 100 million users, comprising 18 million UK members.
It has emerged as a preferred choice to second-hand platforms like eBay and Depop.
This represents another occasion that an unexpected update within the service has received backlash: previously, the service retracted a modification regarding delivery choices due to shopper criticism.
A seasoned casino analyst with over a decade of experience in gaming strategies and industry insights.