Start with the product workflow, not the feature list
The most expensive MVP mistake is treating every idea as a first-release feature. Startup MVP development should begin by identifying the core workflow a customer must complete for the product to create value.
For a SaaS product, that might be signup, onboarding, one core action, reporting, and admin control. For a marketplace, it might be listing, discovery, enquiry, payment, and fulfilment visibility. The shape depends on the business model, but the principle is the same: build around the value loop.