Note from Docker Compose file version 3 reference:
When mapping ports in the HOST:CONTAINER format, you may experience erroneous results when using a container port lower than 60, because YAML parses numbers in the format xx:yy as a base-60 value. For this reason, we recommend always explicitly specifying your port mappings as strings.
https://docs.docker.com/compose/compose-file/compose-file-v3/#ports