Members of the platform have expressed outrage due to a modification that led to items being listed as the wrong size.
This online marketplace has updated its size classifications for women's and children's garments but did not contact all users about the change.
Numerous buyers and vendors are posting online stating that platform listings now display a modified sizing category versus the original listing due to the recalibration.
The company said the new system was more in line with other platforms.
They have suggested members to review their products and adjust the sizing manually if necessary, which has left users frustrated.
Before the change, the sizing featured numerical and alphabetical indicators, like S/8 or M/10.
The new system has a letter with a size spectrum 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, explained the modification "makes transactions more difficult".
"Not many brands say XL is a 20-22," which is what Vinted now does.
Another user, from Glasgow, explained products she uploaded with size 14 tags were displaying on the service as larger sizing 20-22.
"If buyers measuring 20-22 acquire them they're going to be very disappointed," she said.
A different user, located in England, said she had been left angered because the modification necessitated personal updates the sizes on "every single listing".
"For me this is particularly frustrating, as I'm chronically ill and platform income has been essential following partial earnings loss," she explained.
The service features exceeding 100 million shoppers, including 18 million in the UK.
It has proved a popular alternative compared to resale services such as eBay and Depop.
This isn't the first time where an unanticipated change within the service has received backlash: previously, Vinted reversed a change regarding delivery choices due to shopper criticism.