If you stand on top of the base in koth, and aim your bombers bombs right into the crack between the wall and the ground, it is possible to shoot through that barrier. It’s also possible to shoot through the blue/yellow force fields in certain instances. People who do this are not technically hacking, but exploiting bugs in the game that they’ve discovered.
Death within the base, or double death, is a result of ping and odd death circumstances, where your body is randomly slung into the base as it dies. Even though it looks like you’re in the base, you actual self is re-slung onto the place where you died or cap, and shot at briefly. This makes it look like you’re being shot at while in the base, and if you die again, the double death will activate.
Going outside of the moon base map is a very old and known bug, but one that I thought was fixed. Perhaps there is still a small tear to be found. That it’s a bomber that accomplished that, makes it all the more suspicious of being this same old glitch.
You can always consider that most of these people will be using webgl, Perhaps JEEFERSON is trying to give a bad name to JEFFERSON by insulting people with such a similar name.