Hydration errors in React-based applications can be difficult to debug, especially when they occur in production. These errors happen when the markup rendered by React on the client doesn't match the initial server-rendered HTML or when invalid HTML was sent by the server. Sentry, a popular error tracking tool, can help developers debug these issues using its Session Replay feature. By capturing both the server-rendered and client-rendered markup that existed when the error happened, Sentry allows developers to view diffs in visual and raw HTML modes, making it easier to identify discrepancies between the two versions of the HTML. This can be particularly helpful for debugging fake hydration errors caused by invalid HTML.