https://www.cnet.com/news/deadpool-2-post-credits-scenes-explained-what-happens-green-lantern-vanessa-wolverine-ryan/

A lot happens during the credits, so let's get right to it. 

There's a giant 400-pound chimichanga worth of spoilers below. I not only spoil the ending, but pivotal things that happen throughout the film. You've been warned.