The autoincrement was not in sync for some tables on read and write replicas. I was told by our AWS account managers that this was a bug in Aurora mysql version 5. We have upgraded to version 8. Currently we have 8.0.mysql_aurora.3.04.0. The bug was not fixed, or maybe it was fixed and came back again.
Because of this I sometimes have errors on inserts. The autoincrement seems to get in sync on database failover.
As you can see in the images, multiple tables have autoincrement out of sync. Amazon AWS please fix this bug!