WARNING: The following contains spoilers for Dragon Ball Super Chapter 72, by Akira Toriyama, Toyotarou, Caleb Cook and Brandon Bovia, available now in English through Viz Media.
Introduced in the original Dragon Ball, Senzu Beans are one of the most notoriously overpowered items in all of Akira Toriyama's beloved franchise. By eating one Senzu Bean, a warrior can essentially regain all of their strength and recover from their wounds, which has caused the items to play a key role at several major junctures. However, in Dragon Ball Super Chapter 72 -- the latest entry in the manga -- Goku and Vegeta make a critical error in their battle against Granolah by not bringing enough Senzu Beans to Planet Cereal.
At the start of Dragon Ball Super Chapter 72, Goku and Vegeta arrive on Planet Cereal to fight Granolah, believing that he's actually a villain. Soon, they take off to fight Granolah and find themselves under attack from a bunch of long-range energy blasts. Initially, Goku and Vegeta are successful at dodging the blasts. However, Goku soon ends up getting hit in one of his vital points, knocking him out. At this point, Goku and Vegeta haven't even seen Granolah, who has proven too fast for them.
Vegeta rushes to the downed Goku's aid and pulls out a Senzu Bean. "I'd hate to use any of our Senzu Beans before we've even seen our enemy, but eat up, you! We only brought two beans with us." Thus, Vegeta reveals that he and Goku only brought two Senzu Beans for their fight with Granolah. From there, Vegeta chastises Goku for relying only on Ultra Instinct, which is seemingly part of the reason he got hit.
While Senzu Beans are hard to grow, a lot of time has passed since the Z-Fighters' battle with Moro, which means that the supply should have theoretically been replenished. It's entirely possible that Goku and Vegeta opted to not bring more Senzu Beans, thinking that their opponent wouldn't prove nearly as deadly as Granolah already has. Plus, by trying to rely on Ultra Instinct rather than tapping into his full power, Goku has cost them one of their only sources of healing while on Planet Cereal. Either way, having to use a Senzu Bean so soon into their battle with the strongest fighter in the universe is certain to cause a lot of problems for Goku and Vegeta, as he's ruthlessly efficient and out to kill them.
Dragon Ball Super Chapter 73 will release on June 20 through Viz Media.