Issue with instance tags on ec2 module

ec2_playbook.yml

vars:
    key_name: mykey
    instance_type: t2.micro
    security_group: sg-xxxxxxxx
    image: ami-f5b815e8
    region: sa-east-1
    subnet_id: subnet-5eaxxxxx
    instance_tags: 
      - '{"foo": "bar"}'


tasks:
    - name: Launch instance
      local_action: ec2 
                    key_name={{ key_name }}
                    group_id={{ security_group }}
                    instance_type={{ instance_type }}
                    image={{ image }}
                    wait=yes 
                    region={{ region }}
                    assign_public_ip=yes
                    vpc_subnet_id={{ subnet_id }}
                    instance_tags="{{ instance_tags }}" # not working
      register: ec2