for f in *; do echo "$f" done

for f in *; do echo "$f"; done

done only works as a keyword when it's the first token of the command. If added after a command, it will just be the literal word "done".

If you're intentionally using done as a literal, you can quote it to make this clear to shellcheck and human readers, e.g. instead of echo Task is done, use echo "Task is done".