Traefik error: failed to decode configuration from flags: field not found, node: tls

docker-compose.yml
version: '3.7'

services:
    reverse-proxy:
     image: traefik:v2.1.2
     command:
      --providers.docker
      --providers.docker.exposedbydefault=false
      --providers.docker.swarmmode=true
      --entryPoints.http.address=:80
      --entryPoints.https.address=:443
      --entryPoints.mysql.address=:3306
      --accesslog
      --log.level=INFO
      --api=true
     ports:
       - 80:80
       - 443:443
       - 8080:8080
     volumes:
       - /var/run/docker.sock:/var/run/docker.sock
       - /var/cert:/certs/
       - /var/config:/config/
     deploy:
        mode: global
        placement:
          constraints:
            - node.role == manager
        labels:
          - traefik.enable=true
          - traefik.http.routers.traefikRouter.rule=Host(`traefik.bpmspace.net`)
          - traefik.http.routers.traefikRouter.tls=true
          - traefik.http.routers.traefikRouter.service=api@internal
          - traefik.http.routers.traefikRouter.entrypoints=https
          - traefik.http.services.justAdummyService.loadbalancer.server.port=1337
          
     networks:
       - proxy-net

networks:
 proxy-net:
   external: true

The certificates definition:

/config/tls.yml
tls:
  certificates:
    - certFile: /certs/wildcard.bpmspace.net.certificate.crt
      keyFile: /certs/wildcard.bpmspace.net.key

or

/config/tls.toml
[[tls.certificates]]
  certFile = "/path/to/domain.cert"
  keyFile = "/path/to/domain.key"

https://docs.traefik.io/v2.1/https/tls/#user-defined