If standard restarts and toggling notifications didn't bring your watch animations back, the issue is likely tied to a hidden battery saver, a software state glitch, or accessibility settings overriding the UI behavior.
Check Accessibility / Motion Settings: Look in your phone's companion app or watch settings for a Reduce Motion or Remove Animations toggle. If this was accidentally enabled or triggered by a battery profile update, animations will completely cease.
Disable Power Saving / Theater Modes: Ensure Theater Mode, Cinema Mode, or aggressive Battery Saver modes are completely turned off on both the phone app and the watch itself, as these routinely kill non-essential UI transitions to save power.
Unpair and Re-pair the Device: A simple restart leaves corrupted cache files intact. Unpairing the watch completely from your phone and setting it up fresh forces a clean sync of all UI packages and configuration states.