which terraform and aws providers version are you using?

I used terraform v1.5.6 and aws_provider version = ">= 4.67.0" and i applied the same configuration without the ttl, then i added the ttl object, and the plan detected it without any issue:

try to check the configuration within the state file to see wether the ttl is configured there or no using:

terraform state show aws_dynamodb_table.vehicle_id_table

and ensure that the Terraform state reflects the TTL settings.

Also maybe the TTL is already added manually, that's why the plan is not detecting anything. But, terraform detects it without any issue.