Convert:
kubectl run curler --image giantswarm/tiny-tools --serviceaccount app-sa --command -- /usr/bin/tail -f /dev/null
Since --serviceaccount is deprecated. One alternative is using kustomize. Its more work, but a good technique you can reuse for other deprecated options or automation.
kubectl --dry-run=client -o yaml run curler --image giantswarm/tiny-tools --command -- /usr/bin/tail -f /dev/null > curler.yaml
cat < addsa.yaml