Just adding this to the backlog:
If we change our current S3 endpoint
from: https://$BUCKET.s3-$REGION.amazonaws.com
to: https://$BUCKET.dualstack.$REGION.amazonaws.com
we get IPv6 support.
Example:
IPv4 only image:
https://assets-meta-cdck-prod-meta.s3.dualstack.us-west-1.amazonaws.com/optimized/3X/9/d/9d543e92b15b06924249654667a81441a55867eb_1_690x184.png
IPv4 and IPv6 compatible image:
https://assets-meta-cdck-prod-meta.s3.dualstack.us-west-1.amazonaws.com/optimized/3X/9/d/9d543e92b15b06924249654667a81441a55867eb_1_690x184.png