The next release of Scap, our deployment tool, renames the "scap sync" subcommand to "scap sync-world". The sync command should mostly only be used by Release Engineering during train deployments, and SWAT folks updating l10n; everyone else almost certainly wants "scap sync-file" instead. The change is to make it harder to use the wrong command by mistake.
If you know of another use of "scap sync", especially in a script rather then interactive use, please tell me as soon as possible, by leaving a comment on this Phabricator task: https://phabricator.wikimedia.org/T250302
The next release will probably happen within a few weeks. After that "scap sync" will be an error, with a message suggesting "scap sync-world" or "scap sync-file" as a replacement. (Which is OK for interactive use, but might be problematic for scripts.)