Korra and the cataclysm: what the Seven Havens premise establishes

Three different claims

It helps to separate statements that often get compressed into one sentence:

1. A catastrophe happened before Pavi's story.
2. People in the new setting fear or blame the Avatar.
3. Korra personally and deliberately destroyed the world.

The first two are part of the published premise. The third is a much stronger claim and needs its own evidence. An in-world accusation can be important to the plot without being the complete historical account.

What Korra's series actually leaves behind

The Legend of Korra changes the relationship between humans and spirits, and Korra loses her connection to earlier Avatar lives during Book 2. Book 4 ends with another spirit portal opening in Republic City. These are distinct events. Combining them into “Korra broke everything” removes both chronology and cause.

Korra does not lose the ability to be the Avatar merely because the past-life connection is severed. The Avatar State and access to earlier incarnations should not be used as interchangeable terms.

How to evaluate a new theory

Ask where the information comes from: an episode event, a character's account, official publicity, or a fan interpretation. Then ask whether it establishes what happened, who acted, and why. Evidence for one of those questions may not answer the other two.

A viewer theory discussion illustrates the speculation around Korra's reputation. It is useful as a discussion of possible explanations, not as a factual source for the catastrophe's cause.

Read the ending separately

If your question is about the final minutes of Korra's television show, use Korra's ending explained. If your question is whether she is guilty of destroying the later world, use the claim-by-claim guide.