There could be several reasons why the revenue of a nascent e-commerce business has declined 5% w-o-w. One possible reason is a decrease in traffic or conversions on the website. This could be due to a number of factors, such as changes in the algorithm of search engines, a decrease in advertising spend, or a decrease in overall consumer demand. Another possible reason could be an increase in competition from other e-commerce businesses. This could result in a decrease in market share, which could ultimately lead to a decrease in revenue. Other potential reasons could include problems with inventory management, shipping delays, or issues with payment processing. As a product manager, it is important to conduct a thorough analysis of the data and identify the root cause of the decline in revenue in order to develop an effective strategy to address the issue. This could involve conducting user research to identify pain points and areas for improvement, iterating on the product to improve the user experience, or developing a new marketing strategy to increase traffic and conversions. Ultimately, the key to success in e-commerce is a deep understanding of the customer and the ability to iterate quickly based on user feedback and data analysis.