To put it simply, 100% of the time you are able to clip out of the map due to a missing hitbox. This only works on the Gunwitch with proper timing to my knowledge, as it's a pretty high missing roof.

Go to basically under the giant bridge, at the top of the stairs near the crystal. Hit 3 to launch back toward it, and doublejump at the bottom of the bridge. Almost instantly after clipping you want to vroom broom and float toward the stairs that normally go up to the bridge.  And that's basically all you have to do to clip out of the map. I found this out on accident when trying to pick a sniping spot for a guardian that was under the bridge, and found the clip instead as a result.

I used the hover / float trick (every few seconds get off the broom, snipe mode, get on the broom) every few seconds afterwards and managed to get far enough where the map is out of the render distance when i tested the potential of this missing hitbox.  Not sure if it's the type of bug you'd want to fix, but hey, it exists. Sorry if it's in the wrong category.

Note: The dryad MIGHT have a way to do the clip as well, but I highly doubt it, as this relies on ability 3 AND the double jump for the gunwitch method I provided. Maybe the EV2 as well. I only have unlocked the Gunwitch so far, so I cannot test other heroes with launching abilities yet or with double jumps.