Gitlab Runner 16.2.0 jsonschema: '/runners/0/docker/ulimit' does not validate ... expected object, but got null

I want to migrate an existing Gitlab instance to another server. Today, I've updated Gitlab and Gitlab-Runner from 15.3.3 to 15.6 to 16.2. After upgrading the Gitlab runner, I get the following Warning/Error:

There might be a problem with your config based on jsonschema annotations in common/config.go (experimental feature):
jsonschema: '/runners/0/docker/ulimit' does not validate with https://gitlab.com/gitlab-org/gitlab-runner/common/config#/$ref/properties/runners/items/$ref/properties/docker/$ref/properties/ulimit/type: expected object, but got null

I did not set docker.ulimit anywhere and want to stay with default values. As I can see, it's related to this MR: #4482 (closed).

Here are some specs if needed:

[root@server gitlab-runner]# cat config.toml
concurrent = 8
check_interval = 0

[session_server]
  session_timeout = 1800

[[runners]]
  name = "brandbox-docker-ciexecutor"
  url = "https://git.domain.tld/"
  token = "<TOKEN>"
  executor = "docker"
  [runners.docker]
    tls_verify = false
    image = "<IMAGE>"
    privileged = false
    disable_entrypoint_overwrite = false
    oom_kill_disable = false
    disable_cache = false
    volumes = ["/var/run/docker.sock:/var/run/docker.sock", "/cache"]
    shm_size = 0
  [runners.cache]
    [runners.cache.s3]
    [runners.cache.gcs]

[[runners]]
  name = "brandbox-shell"
  url = "https://git.domain.tld/"
  token = "<TOKEN>"
  executor = "shell"
  [runners.cache]
    [runners.cache.s3]
    [runners.cache.gcs]

[root@server gitlab-runner]# cat /etc/os-release
NAME="Ubuntu"
VERSION="18.04.6 LTS (Bionic Beaver)"
(...)