Questions regarding Captain Marvel's long absence from the MCU's Earth have already been secretly answered in Phase 5's Secret Invasion. Although Secret Invasion has become the lowest-rated of Marvel Studios' Disney+ TV shows, the series did include several major revelations that will change the shape of the MCU forever. After the events of 2019's Captain Marvel, many shape-shifting Skrull refugees were left on Earth, waiting in the hopes that Nick Fury and Carol Danvers would find them a new home across the stars. Secret Invasion revealed that they were unable to keep their word, which raised further questions concerning Danvers' absence from the MCU.

In a drastic change from Marvel Comics, the MCU's Skrulls were revealed to be peaceful allies to humanity in Captain Marvel, a species seeking asylum after the destruction of their home world, Skrullos. While Nick Fury and Captain Marvel promised to find the Skrulls a new home, Secret Invasion revealed that, not only did they fail to keep their word, but Nick Fury had been exploiting the Skrulls for their shape-shifting ability since the 1990s. While it was initially unclear why Fury and Danvers hadn't been able to relocate the Skrulls, one major reveal in Secret Invasion episode 2 proved that the situation is much more dire than first suspected.

Captain Marvel's Skrull Task Is Way Harder Than We Thought

Secret Invasion episode 2, "Promises," saw Talos reveal to Fury that, far be it from the handful of Skrulls first thought to be living on Earth, a million Skrull refugees had in fact been living among humanity. Secret Invasion's million Skrulls reveal made Fury and Danvers' task seem impossible, as it might have been easy to relocate a few refugees, but moving a million Skrulls off-world is a more daunting mission. Fury even mentions during Secret Invasion that the task to find the Skrulls a new home was far more difficult than they had previously thought, which could explain exactly why Captain Marvel stayed away from Earth for so long.

Secret Invasion Justifies Captain Marvel Being Gone For So Long In The MCU

It's very likely that Carol Danvers had been searching for a new home for the Skrulls during her thirty-year absence, but the fact that her mission involved relocating a million Skrull refugees made this difficult. Humanity housed the Skrulls unknowingly, but if Fury and Danvers were going to be more ethical, a new society would need to agree to take in the Skrulls - who also have a reputation as fierce and dangerous warriors. Based on this, it would likely be a challenge for Danvers to convince a peaceful society to accept an entire civilization of Skrulls into their ranks.

Captain Marvel's absence from Earth could simply be explained by her not wanting to return to the Skrulls with bad news. Perhaps she felt guilty that she hadn't been able to keep her promise, feeling more compassion for the Skrulls' situation than Nick Fury did, as the latter had only used the Skrulls for his own purposes on Earth. After the events of Secret Invasion, it seems as though the United States has declared war on the Skrulls on Earth (and any off-world species for the matter), which means that Fury and Danvers' failure to keep their promise could have put the Skrull refugees in even more danger than before.