User defined routes (UDR) and smaller required subnet sizes are now available in public preview for Azure Container Apps on the Consumption + Dedicated plan structure.
You can define UDRs to manage how outbound traffic is routed to your container app environment’s subnet by enabling network appliances such as firewalls on the new Consumption + Dedicated plan structure.
In addition, with the new plan structure, the minimum subnet size required is a /27 CIDR. A minimum subnet size of /23 is still required for container apps created on the existing Consumption plan.