[US] Got scammed on mercari and vendor wants to refund me on Cashapp afterwards. Worried I was added to a “Suckers List”

A user purchased an item on Mercari, but the package was returned due to postal issues. The vendor communicated via Instagram (against Mercari's TOS) and later offered a refund through Cashapp or Zelle, raising concerns about potential scams. The user also received a suspicious Instagram message from an unknown account, prompting fears of being targeted on a 'suckers list.'