Note that periodic_sync is in seconds

mautrix_signal/example-config.yaml

@@ -179,7 +179,7 @@ bridge:
     # This field will automatically be changed back to false after it,
     # except if the config file is not writable.
     resend_bridge_info: false
-    # Interval at which to resync contacts.
+    # Interval at which to resync contacts (in seconds).
     periodic_sync: 0
 
     # Provisioning API part of the web server for automated portal creation and fetching information.