Physical dust or grime on the gold plates of your SIM card can cause data transmission errors.
The system app managing the toolkit might be stuck in a loop. The "Bring It Back" Playbook Android Sim Toolkit Not Working
The SIM Toolkit (or STK) isn't like a normal app you download; it’s an interface for small applications physically stored on your SIM card. When it breaks, it’s usually because the communication between the Android OS and that tiny chip has been interrupted by: Physical dust or grime on the gold plates