Saw a distant light moving slowly and then rapidly accelerated horizontally, eventually disappearing.

As I was leaving a family member’s house, I stopped in the driveway with my girlfriend to stargaze for a few minutes. We usually like to pick out constellations, identify satellites, and can sometimes see the faint glow of the Milky Way - on especially clear nights. I am not an expert, by any means, but I do love to stargaze and can tell the difference between comets, planes, satellites, etc.
While looking SE, at roughly a 30 degree angle, I noticed what I first thought was a satellite moving relatively slowly and in a horizontal line across the sky. After moving at this rate for about 3 seconds, the white object accelerated at an incredible speed, and then disappeared.
I thought that it could be a shooting star, but when I’ve seen them, they last about a second and are moving rapidly the entire time. The object I saw, in this instance, picked up speed at a quite unbelievable rate. Another thing that set this experience apart was how long I was able to see it - 5 seconds is much longer than the length one would see a shooting star.
I also considered the possibility that it could be a satellite. However, when I’ve seen satellites, the light is much dimmer than what I saw, in this instance, they move at a uniform speed, and you can track them throughout their journey in the sky. This light was only visible for a few moments and disappeared while there was plenty of sky left.
I would say I am a UFO/UAP skeptic, but seeing this object compelled me enough to actually think a report may be useful. Maybe I am missing something here, but it was extremely impressive. I again would like to reiterate just how quickly this object accelerated. Not to be cliche, but it was like seeing a light moving at the speed of a plane, and then it accelerated like the Millennium Falcon jumping into hyperspace - no joke meant here, but I feel like it is a good analogy to really help illustrate its speed.