When you say “Copy” - did you copy it via a Backup Copy job or by copying the files?  If the latter then that is not a good method and should set up a copy job.  If this is done right you can add the S3 to VBR and import the backups.

it’s by coping the files

File Copy Job or Manual copy?  If manual copy this is why you are having issues more than likely.  Set up a Backup Copy job or File Copy job in Veeam to do the work for you and make things easier.

it’s manually copy. we just take the backup to an external hdd and give this hdd to the vendor, the copy the backup to bucket 

Well, that is the problem.  Veeam needs to do the copy to S3 in order to place the files properly so it can recognize them within the VBR Console.  So, this method will always have issues unfortunately.

is there any way recover it now?

If Veeam is not reading the files properly then there will not be.  Again, this is not a method I would use and use Veeam to get the files to your S3 instead to ensure recoverability.

You can try copying the files down and use the Veeam Extractor utility to see if you can read the VBK files or not but that would be the only thing I can think of to test the files since this was done in a sub-optimal way.

Did you try to copy the data back from S3 to a harddisk, and then try to add those backups with import backup in the VBR console?