LND version 0.18.5 is currently not available in the Umbrel App Store, do you use a different store or did you upgrade using the terminal?
On mine it is, version 0.18.5-beta, same as on the GitHub, on the app store, all standard repo as far as I know.
Check with Umbrel support if you don't see the update.
Check with Umbrel support if you don't see the update.