Dragon Ball Super started off with Goku having to face a new level of opponent in Beerus, the God of Destruction. That fight pushed Goku to a new godly level of Saiyan power, but ultimately his battle with Beerus ended in a stalemate (and later a tenuous truce), as the God of Destruction fell asleep. Since then, many Dragon Ball Super fans have speculated that a rematch between Goku and Beerus is inevitable. Now, the latest chapters of Dragon Ball Super's manga has brought Goku to a new milestone of god-like power, and it seems more likely than ever that Beerus could feel it's time for a rematch!
Warning: Dragon Ball Super manga SPOILERS Follow!
The "Galactic Patrol Prisoner" arc of Dragon Ball Super unleashed a new threat to the universe in the form of "Planet-Eater" Moro, an ancient sorcerer that pushed the gods themselves to the brink before he could be locked away by the Galactic Patrol. Once loose, Moro terrorized the universe consuming lives of entire plants - and he almost killed both Goku and Vegeta in battle, twice, despite each Saiyan hero achieving new (respective) power-ups. When Earth was nearly consumed by Moro, it was Goku's angelic mentor Merus who stepped in to sacrifice himself and give Goku one last chance to achieve the near-impossible: Perfected Ultra Instinct. Goku being Goku (and Dragon Ball being Dragon Ball), Merus death is all the inspiration Goku needs to finally master Ultra Instinct's complete form.
Moro doesn't stand a chance against Ultra Instinct Goku. Not only are the Saiyan's offensive and defensive powers boosted to the max, his uniquely-developed special techniques (like that anti-Broly energy snare) are also boosted to the point that Moro is easily thrashed. After seeing the Saiyan in battle, even Beerus must respect what Goku has achieved with Ultra Instinct.
Therein may lie the problem. Anyone who knows Lord Beerus knows that seeing Goku achieve a god-like power that could challenge Beerus himself is all the provocation the God of Destruction needs to assert his alpha status once again.
In fact, Goku's Ultra instinct status has raised major questions for the future of Dragon Ball as a whole. Goku has broken through to a new plane of power and control that makes it increasingly hard to believe the divine powers of the multiverse won't take notice or issue with. That could lead to Saiyans vs Gods arc that Dragon Ball fans have been waiting for.