Clean up tool is not working on my iPhone 15 Pro Max

Have you tried quitting the app and reopening the app? Have you done a forced restart of your iPhone? The Apple Support article linked below explains step by step the procedure.

Force restart iPhone - Apple Support

iOS 18.2 public release is rolling out around the world in many (all?) countries today. I watched a video from someone in Australia an hour ago and he’d installed the update and reported that it resolved many of his issues. The article below explains how to update. The release time in your area may not have occurred yet. You will just need to check the update option in your iPhone.

Update iOS on iPhone - Apple Support