Okay, the docker autodiscovery appears to be different with version >8.12 (see: Filebeat Docker Autodiscovery stopped working when I upgraded to 8.12.0 - #10 by Michalis_Katsoulis).
I've modified my config:
filebeat.autodiscover:
providers:
- type: docker
hints.default_config:
paths:
- /var/lib/docker/containers/${data.container.id}/*.log
type: container
hints.enabled: true
Now it seems to be working.