Members of the platform have expressed outrage after an update resulted in listings displaying inaccurate size information.
The second-hand shopping app has revised its sizing categories for women's and children's clothes failing to inform all shoppers about the modification.
Many shoppers and sellers are expressing on platforms stating that platform listings now display a different size category versus the original listing as a result of the reclassification.
Vinted explained the new system was more in line with comparable marketplaces.
The platform has recommended to examine their items and manually change the size where appropriate, resulting in member annoyance.
Earlier, the sizes had both one number and one letter, for instance S/8 or M/10.
The new system has a letter with a size spectrum like S/UK 8-10.
In some cases, the measurements have been reclassified - such as a large size was previously a 12 but is now a UK 16-18.
A fashion influencer, who creates plus-size fashion videos, said the change "makes both selling and buying harder".
"Few clothing companies classify XL as 20-22," which is what Vinted now does.
Another user, based in Glasgow, explained products she uploaded featuring size 14 markings were showing in the marketplace as larger sizing 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 because the modification necessitated personal updates the sizes on "every single listing".
"This situation is especially annoying, because of my ongoing medical condition and platform income has been essential for me since losing part of my income," she explained.
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 is not the initial instance when a surprising modification on the platform has faced criticism: last year, the platform withdrew an update regarding delivery choices following member complaints.
Elena Rossi is a cloud technology expert with over a decade of experience in data security and digital transformation strategies.