Members of the platform have expressed outrage due to a modification that led to listings displaying inaccurate size information.
This online marketplace has altered its sizing categories for female and kids' apparel but did not contact all shoppers about the modification.
Many shoppers and sellers are expressing on platforms claiming that product pages now present an altered size classification versus the original listing due to the recalibration.
The platform stated the revised method more closely matches comparable marketplaces.
It has advised users to check their listings and adjust the sizing manually when needed, causing user dissatisfaction.
Previously, the measurements included a single numeric size and a letter, for instance S/8 or M/10.
The updated approach includes a letter with a size spectrum for example S/UK 8-10.
In some cases, the measurements have been reclassified - like an L measurement was previously a 12 but currently displays as UK 16-18.
One content creator, who creates plus-size fashion videos, said the change "makes both selling and buying harder".
"Not many brands say XL is a 20-22," which is what Vinted now does.
Stephanie Gallen, based in Glasgow, stated items she posted featuring size 14 markings were showing in the marketplace as measurements 20-22.
"If buyers measuring 20-22 acquire them they're going to be very disappointed," she said.
Another shopper, based in Derby, explained she became annoyed by the change as she had to manually change the sizes on "every single listing".
"For me this is particularly frustrating, as I'm chronically ill and platform income has been essential for me since losing part of my income," she said.
The app has more than 100 million members, with 18 million British users.
It has become a favored option compared to resale services such as eBay and Depop.
This isn't the first time that an unexpected update within the service has received backlash: last year, the platform withdrew an update regarding delivery choices due to shopper criticism.
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