Motionless cat: if Windows “Animation effects” were turned off, your cat froze: it stopped roaming and ignored clicks. It now roams and reacts normally, regardless of this setting.
Animated decors: in the same situation, animated decors stayed still on the desktop, as did the interactive preview of “Pumpkin Lantern Dance”. They now animate normally.
Bug reports: reports now include whether Windows reduces animations, to help us diagnose this kind of issue faster.
To keep your cat still, use “Pause roaming” in Settings. Thank you for your reports and for helping us improve My Desktop Cat!