Mistakes happen all the time. You delete an entry you didn’t want to delete, you import the same file twice, you do some unwanted change you really did mean. The are also other things that could potentially happen to a vault, such as the database becoming corrupted and hence not possible to decrypt.
Hence I would suggest Bitwarden to automatically make backups of the vault for the user to download or just have as “restore points”.
I think this is a free feature on last pass no less. Been using Bitwarden since last summer and I assumed this was a thing in the background just haven’t had the need to check yet, so there really is no backups being saved anywhere and we have to manually do it?