krayt dragon that Mandalorian Din Djarin agreed to slay in his deal with Cobb Vanth occupied a former sarlacc pit. When the Marshal doubted there could be a truly abandoned sarlacc pit, Djarin responded, "There is if you eat the sarlacc." Since the sarlacc was the most fearsome beast in Jabba the Hutt's menagerie of monsters, the one he chose for Luke Skywalker's execution when the rancor proved ineffective, it's a marvel that another predator was able to defeat it.
The sarlacc's weakness lies in the way it consumes its prey. According to Jabba, the sarlacc's victims are slowly and painfully digested over a thousand years. It operates more like a carnivorous plant than a hunter, ensnaring any prey unfortunate enough to fall into its mouth, immobilizing it, and breaking it down over time. The krayt dragon, by comparison, is an active hunter. It emerges from beneath the sand to swallow banthas whole and sprays acid on its attackers. Although everyone on Tatooine seems to know the sarlacc is best avoided, the krayt dragon is much more difficult to avoid and took out most of the Mandalorian's hunting party with little effort.
Given these advantages, the krayt dragon would be the apex predator of Tatooine, even feared most by the Tusken Raiders. Once the krayt dragon set its sights on the sarlacc, the sarlacc didn't stand a chance. It's not highly mobile like the krayt dragon, and a greater krayt dragon the size of the one the Mandalorian took on may have even swallowed the sarlacc whole. The sarlacc doesn't have many tools to defend itself against a large, active predator, and it likely met a swift demise. Since Din Djarin was able to bring down the far more vicious krayt dragon with explosives, his jetpack, and the protection of his Mandalorian armor, Boba Fett's escape from the Sarlacc is less miraculous than it might seem.
While fans have long theorized Mandalorian armor survived the krayt dragon's virulent acid. If the Mandalorian could take down a krayt dragon with the same tools at Boba Fett's disposal, Boba Fett could easily get away from the weaker sarlacc.
The Mandalorian's expansion of the Star Wars universe brings many new creatures into canon, and many of them are worse threats than the sarlaccs, rancors, and wampas that have appeared before. The bounty hunter is prepared for a battle, and the excellent special effects can finally bring these huge and fearsome creatures to life on screen, so the show has leveled up the caliber of the monster the characters encounter. The krayt dragon may still be nothing compared to the creatures yet to come on The Mandalorian.