If we suspend the constraints of reality and assume teleportation is possible, traveling at an infinite speed, let's examine the scenario you presented. Suppose we teleport from Earth to a planet located 4 light years away, and then immediately teleport back to Earth.
In this hypothetical situation, the distance between Earth and the target planet is traversed instantaneously due to the assumption of infinite speed. Therefore, no time would pass during the teleportation process itself. Consequently, when you arrive back on Earth, you would technically have not experienced any time passing.
However, it's important to note that from an external perspective, time would still have progressed during your absence. While you would have experienced no time passing during the teleportation, Earth would have continued its orbit around the sun, and time would have elapsed for everyone else.
So, when you return to Earth after your instantaneous journey, you would find that a certain amount of time, specifically 8 years, has passed on Earth while you were away. In this sense, you would not have traveled into the past, but you would have effectively skipped 8 years of Earth's timeline.
Remember, this is purely a hypothetical scenario based on the assumption of impossible conditions, and it doesn't align with our current understanding of physics.