Shoppers are voicing their frustration after an update resulted in listings displaying inaccurate size information.
The popular resale platform has updated its size classifications for women's and children's clothes without notifying every member regarding the update.
Many shoppers and sellers are posting online stating that platform listings now display a different size category compared to what was initially listed as a result of the reclassification.
The company said the updated approach better aligns with other platforms.
It has advised users to check their listings and manually change the size where appropriate, resulting in member annoyance.
Earlier, the sizes had both a single numeric size and a letter, like S/8 or M/10.
The revised method features a letter and a range like S/UK 8-10.
In some cases, the size labels have been reassigned - for example a size L was previously a 12 but now shows as UK 16-18.
A fashion influencer, who produces content about larger sizing, said the change "makes both selling and buying harder".
"Not many brands say XL is a 20-22," the way the service now categorizes.
Stephanie Gallen, from Glasgow, stated items she posted with size 14 tags were appearing on the platform as measurements 20-22.
"If buyers measuring 20-22 acquire them they will likely be quite upset," she explained.
Charlotte Lunn, from Derby, explained she became annoyed by the change as she had to manually change the sizing for "all her products".
"Personally, this is quite irritating, since I have chronic health issues and platform income has been essential following partial earnings loss," she stated.
The platform boasts over 100 million users, with 18 million British users.
It has become a favored option compared to resale services such as eBay and Depop.
This represents another occasion when a surprising modification within the service has received backlash: previously, the platform withdrew an update to its shipping options following member complaints.