REALLY DISSAPOINTEDAs a long-time seller on Mercari (5-star rating since 2019), I'm frustrated with their mandatory third-party authentication for certain items. It feels unnecessary, especially since the $5 fee cuts into profits.Recently, an item I knew was authentic was flagged as inauthentic. When I questioned this, Mercari offered no explanation, only that their third-party service had the final say. Mind you their third party authenticators are called 'Real Autheticators' who have some of the most foolish reviews. This is concerning, particularly since other platforms like Vestiaire Collective handle authentication in-house for free.Mercari's reliance on third-party services with poor reviews further undermines trust in the process. To top it off, their customer support uses unhelpful AI chatbots.Overall, this experience has been disappointing. Mercari's authentication system lacks transparency and feels like an unnecessary burden on sellers.