Members of the platform have expressed outrage following a change that caused items being listed as the wrong size.
The popular resale platform has altered its size classifications for female and kids' apparel failing to inform all users about the change.
Countless users and merchants are expressing on platforms stating that platform listings now display a different size category compared to what was initially listed because of the remapping.
The company said the revised method more closely matches comparable marketplaces.
It has advised users to check their listings and manually change the size where appropriate, which has left users frustrated.
Previously, the sizes had both numerical and alphabetical indicators, like S/8 or M/10.
The new system has an alphabetical indicator and numerical range like S/UK 8-10.
In some cases, the measurements have been reclassified - for example a size L was previously a 12 but is now a UK 16-18.
A fashion influencer, who produces content about larger sizing, stated the update "complicates both purchasing and selling".
"Not many brands say XL is a 20-22," which is what Vinted now does.
Stephanie Gallen, from Glasgow, explained products she uploaded on Vinted with size 14 labels were appearing on the platform as larger sizing 20-22.
"If anyone [who is] size 20-22 buys them they will likely be quite upset," she stated.
A different user, from Derby, said she had been left angered because the modification necessitated personal updates the measurements for "each individual item".
"Personally, this is quite irritating, as I'm chronically ill and platform income has been essential for me since losing part of my income," she explained.
The platform boasts over 100 million shoppers, comprising 18 million UK members.
It has become a favored option compared to resale services such as eBay and Depop.
This represents another occasion when a surprising modification to the app has proved unpopular: previously, the platform withdrew an update to its shipping options after backlash from users.
Maya is a tech journalist and digital strategist with over a decade of experience covering emerging technologies and their impact on society.