Wasabi is designed to provide eleven nines (99.999999999%) durability of objects over a given year. More details on durability and other aspects of Waasabi's data protection capabilities can be found in this paper.
As with any environments, the best practice is to have a backup and to put in place safeguards against malicious or accidental user errors. This best practice approach includes secure access permissions, versioning and a functioning, regularly tested backup. In addition, Wasabi provides durability and compliance at the storage bucket level to prohibit deletion of the data in a bucket.