The team has pushed an update that will allow resets to correctly remove data in the final tables for streams with Incremental | Append sync modes.
If you see duplicate data in your destination and you had Incremental | Append sync, running a reset will remove those duplicates and run a fresh, from scratch, sync. Please reach out to Cloud support via in-app chat or in-app webform if you need to run a reset due to this issue and credits will be reimbursed.