Well this was an unwelcome attack vector, since I wrangle a fair few S3 buckets. I hastily threw together an S3 bucket name generator in Bash under Linux [1] to create names that follow the AWS rules to start my migration to my new S3 bucket names, and welcome any help to ensure it creates names that are strongly resistant to this attack, and follow various S3-service-like vendor rules, so I can do what I can until AWS and others come out with a stronger defense.
[1] https://github.com/automaticit-anthonyyen1/s3-bucket-name-ge...