Individually harmless, but collectively they form a fibrous "bird's nest" that clogs the impeller. Dental floss is particularly dangerous because it is long, strong, and non-biodegradable.
Spray the inside of the tank, the blade, the impeller, and the float switches with a hose (outside) or with a dedicated cleaning solution (Saniflo makes a descaler, but white vinegar and hot water also work for grease). Remove every visible particle. blocked saniflo
Remember: when the motor hums and the water doesn't move, stop, unplug, and think before you flush again. Your basement (and your sanity) will thank you. Individually harmless, but collectively they form a fibrous