Arrange the chicken breasts in a single layer at the bottom of the slow cooker. There's no need to grease the pot.

Sprinkle the entire packet of taco seasoning evenly over the chicken, coating all sides as best you can.

Pour the entire jar of salsa over the seasoned chicken. Make sure the chicken is mostly covered. Don’t stir it; just let it sit on top.

Cover the crockpot and cook on LOW for 6 to 8 hours or on HIGH for 3 to 4 hours. The chicken is done when it’s cooked through and tender enough to shred easily with a fork.

Once cooked, remove the chicken breasts from the crockpot and place them on a cutting board. Use two forks to shred the meat. It should fall apart with very little effort.

Return the shredded chicken to the slow cooker and stir it into the sauce. Let it soak up all that delicious liquid for about 10 more minutes before serving.

For the Instant Pot method, layer the ingredients in the pot with the salsa last to avoid a "burn" notice. Secure the lid and turn the steam release valve to the "Sealing" position. Pressure cook on HIGH for 12 to 15 minutes depending on the thickness of the chicken.

Allow the pressure to release naturally for 10 minutes before performing a quick release for any remaining pressure.

Remove the chicken, shred it with two forks, and return it to the pot. Stir the shredded chicken into the sauce to let it absorb all the flavors.

Preheat the oven to 400°F (200°C). Place the chicken breasts in a 9x13 inch baking dish and sprinkle with the taco seasoning.

Pour the jar of salsa over the chicken. Bake uncovered for 25 to 35 minutes or until the chicken is cooked through and the internal temperature reaches 165°F (74°C).

Let the chicken rest for a few minutes before shredding it directly in the baking dish or on a separate board. Mix the shredded chicken back into the pan juices and serve.