The wires are simply using the receptacle as a splice point. This would be the equivalent of the three wires joining in a splice with a fourth wire that comes out to the receptacle.
Now, when extracting thes wires from the old receptacle, grab onto one wire firmly and twist back and forth about 45 degrees while pulling very firmly. The wire will walk out of the backstab. It may help to jab a release slot, if there is one, but I find them unreliable (as I do backstabs generally). Once a wire is extracted from a backstab, the device is scrap.)
Never cut wires, because wire length is precious. You need 3" beyond the surface of the wall, or you must replace the entire cable run. You don't have length to spare here.
The two best ways to handle this are.
Go back to the store and get a Leviton commercial style receptacle, or competitor, which has a "Screw-to-clamp" attachment method. In this, each screw has 2 back-wire holes directly beneath it. The wires can go into those holes, but they won't grab. You tighten the screw very firmly to clamp the wires. There are 2 wire holes under each screw, so it can accommodate four per side.
This will require some short lengths of wire, and either red wire nuts or some lever-action splice connectors with four voids.
You connect the three wires together with about an 8 inch long pigtail wire. Attach the wire to the side of the receptacle.