Probably something like

(1) Scammer sends check / something like that, showing a larger than expected deposit

(2) Check is cached by victim

(3) Victim is asked to reimburse the difference using Zelle or other "irreversible" method (best being Bitcoin, I guess, but Zelle also works apprently..)

(4) Check bounces

(5) Victim looses the money send by Zelle