Tech debt does not go away on its own. Teams acknowledge it, add it to a backlog, and then continue shipping features because the debt items are never urgent enough to displace the current sprint's priorities. Over time the debt grows until it starts visibly slowing feature development — at which point it is much harder to address.
The challenge with tech debt is that it is hard to make continuous progress on it when sprints are focused on new features. Small amounts of debt remediation done consistently are more effective than large-scale refactoring sprints scheduled annually. But small amounts of anything are hard to prioritize.