add some time for settling down

src/upgrade.py

@@ -4,6 +4,7 @@
 """Manager for handling Kafka in-place upgrades."""
 
 import logging
+import time
 from typing import TYPE_CHECKING
 
 from charms.data_platform_libs.v0.upgrade import (
@@ -101,6 +102,9 @@ def _on_upgrade_granted(self, event: UpgradeGrantedEvent) -> None:
         logger.info(f"{self.charm.unit.name} upgrading service...")
         self.charm.snap.restart_snap_service()
 
+        # Allow for some time to settle down
+        time.sleep(60)
+
         try:
             logger.debug("Running post-upgrade check...")
             self.post_upgrade_check()