Many newer pills have protective coatings that won’t dissolve in water, to prevent basement chemists from converting them into shit like meth…

Those sort of pills are designed to dissolve in stomach acids, so the warm water test isn’t a universal check.

Honestly I think another commenter hit the nail pretty close on the head though, I think their mom was secretly super depressed and tried to end her own life, but since she survived, she doesn’t want to talk about it.