AWS-Cloudformation: Ipv6 EC2 Route in a Private Nat Subnet - Provide one of DestinationCidrBlock or DestinationIpv6CidrBlock and a valid routeTableId

I am currently creating a network infrastructure within my vpc, that has private subnets and has a NAT gateway. I have a Route Table that has the private subnets associated to it and I intend to have 2 ec2 routes for an ipv4 and ipv6. I have successfully deployed the ipv4 but the challenge comes in with the ipv6.

I am aware that for the ipv6 ec2 route, I need an EgressOnlyInternetgateway and this is referenced in my ec2 route as shown below.

While deploying my templates i get this first with only the EgressOnlyInternetGatewayId;

Resource handler returned message: "You must provide one of destinationCidrBlock or destinationIpv6CidrBlock or destinationPrefixList and a valid routeTableId"

Next I try to add to my template DestinationIpv6CidrBlock: '::/0'. I get this as a new error;

Resource handler returned message: "The request must contain exactly one of gatewayId, localGatewayId, carrierGatewayId, natGatewayId, networkInterfaceId, vpcPeeringConnectionId, egressOnlyInternetGatewayId, transitGatewayId, vpcEndpointId, coreNetworkArn or instanceId

What does aws cloudformation expect in this case, having only EgressOnlyInternetGatewayId or EgressOnlyInternetGatewayId and DestinationIpv6CidrBlock, since neither works.

PrivateNatRouteTable:
    DependsOn: 'NatGateway'
    Type: AWS::EC2::RouteTable
    Properties:
      VpcId: 
        Fn::ImportValue:
          !Sub '${Product}-VpcID'
      Tags:
        - Key: Name
          Value: !Sub '${Product}-private-nat-rt'

Ipv6EgressOnlyIgw:
    Type: AWS::EC2::EgressOnlyInternetGateway
    Properties:
      Tags: 
        - Key: Name
          Value: !Sub '${Product}-ipv6-egress-only-igw'

      VpcId: 
        Fn::ImportValue:
          !Sub '${Product}-VpcID'

  PrivateNatRoute1:
    DependsOn: 'Ipv6EgressOnlyIgw'
    Type: AWS::EC2::Route
    Properties:
      DestinationCidrBlock: '0.0.0.0/0'
      NatGatewayId: !Ref NatGateway
      RouteTableId: !Ref PrivateNatRouteTable

  PrivateNatRoute2:
    DependsOn: 'PrivateNatRoute1'
    Type: AWS::EC2::Route
    Properties:
      EgressOnlyInternetGatewayId: !Ref Ipv6EgressOnlyIgw
      NatGatewayId: !Ref NatGateway
      RouteTableId: !Ref PrivateNatRouteTable

I also have to add i have tried manually adding this route manually and was successful and trying to use aws cli to describe the route-table to see the resource once created manually and i see sth similar to what I have in my template.

{
  "DestinationIpv6CidrBlock": "::/0",
  "EgressOnlyInternetGatewayId": "eigw-s0000000",
  "Origin": "CreateRoute",
  "State": "active"
}