To investigate a 25% drop in free sign-ups on a platform like Notion, I would begin by analyzing the data to pinpoint when the decline began and whether it correlates with specific events or changes. It's crucial to examine information from various sources, including web analytics, team input, customer service feedback, and user reviews. A potential reason for the decline could be technical problems, such as issues with the sign-up process or website outages, which may deter users from registering. If this is the case, improving the sign-up experience, resolving bugs, and enhancing website performance could be effective solutions. Another likely factor could be heightened competition. If rival companies have launched new features or reduced their prices, users may have shifted to those platforms. To address this, Notion might consider updating its features or pricing strategy, or emphasizing its unique advantages and superior offerings. Lastly, poor marketing could result in fewer sign-ups. For example, if marketing activities were scaled back during the decline or did not effectively target the intended audience. In such situations, revitalizing and amplifying marketing efforts could help improve sign-up numbers.