YOUR NEXT STEP
macOS needs about 15-20GB of 'breathing room' to move files around and manage memory. When the drive is full, the system grinds to a halt.
You need to offload photos to an external drive or delete large files immediately. If 'System Data' is the culprit, we can help clear those hidden caches.
A symptom can have more than one cause. These guides help you choose a next step; confirming a hardware fault requires testing.