Why servers fall behind
Each language a project turns on with loom add has a language server, the package that checks that language's sections in your editor. Loom keeps the servers in .loom/services, and each one must match the version of Loom that runs it. Upgrading Loom doesn't touch them, so they stay at the old version until you update them.
Updating
Name the languages to update, or update all of them with . For each language, Loom installs its server if it's missing, replaces it if it's at another version, and leaves it alone if it's current. Git ignores .loom/services, so a fresh clone has no servers yet, and the same command installs them.
loom update works only on languages that are already on. Turn a language on with loom add, and see which servers are out of date with loom status. Restart your editor's language server afterwards, so it loads the new ones.