Vegito vs Kefla

[Hiromi]

Again, Shin noted that he funneled all his energy into one attack in hopes of putting Zamasu down with it, we've seen other attacks by other characters have a similar effect

so basically unless he does the same attack again it shouldn't be an issue as Kefla doesn't have remotely the same kind of durability as Zamasu had

[The Arbiter]

It should be noted that Kefla also defused swiftly after her final attack where she was dumping out like all her energy in one go as well.

Maybe it was Gokus kamehameha that broke the potara, maybe it was her landing into the ring out teleportation area. But the attack explanation is my favorite as it at least fits with Vegitos thing.

Either way, a tired Goku using Blue and KK was about even with ssj1 kefla. I dont think kefla ssj2 can keep up with a fresh Vegito.