Long Travel Soft Brake Pedal

The pad that faces the piston should have a "pin" that fits into a "slot" in the piston, to stop the piston turning/unadjusting .
The pin missing the slot can cause 2 issues.

If the pin misses the slot, it will interfere with the pad making full contact with the rotor, may cause pad to "absorb/bend" till you get pedal. (Soft pedal/extra travel)

If the pin misses the slot, the piston may turn when you release emergency, allowing the pad to "relax" too far, undoing the adjuster, sorta, causing extra pedal travel.

Good luck

P.S. A pad not properly seated in the caliper can cause soft, extra travel.