To fix the routing issue and restore the VM connectivity.
Symptoms:
Decommissioning the HCX components after unextending the segment successfully via HCX, the segment on the SDDC is switched to ROUTED.
The segment CIDR fails to advertise out the Direct Connect or Transit Connect (SDDC Group) interfaces.
This can occur if the un-extended segments from the SDDC are not deleted. And since the Transit connect-->advertised routes are missing the connectivity is wrongly routed via connected VPC-->advertised routes.
Follow the steps mentioned in the doc: Uninstalling HCX in VMware Cloud on AWS Deployments to delete the un-extended segment (refer to point-4).
Post deleting them, the routes get updated and the connectivity is restored.
If the above resolution doesn't resolve the issue, contact Broadcom Support.
The VM workloads connectivity is affected as the routes are missing.