Marketplace businesses generally take roughly twice as long to reach product-market fit as B2B SaaS businesses do, per Casey Winters' work advising both types of company. Concrete examples: Thumbtack (marketplace) took about 4 years to reach PMF; a B2B SaaS client of Casey's reached it in about 6 months. The likely mechanism is that a marketplace must achieve fit on both sides of a two-sided market (supply and demand) simultaneously, roughly doubling the search space compared to a single-sided SaaS product.
Relates to Demand-First vs. Supply-First Marketplace Launch Strategy, which describes how marketplaces sequence solving each side, and to Business Model Category Is a Red Herring for Second-Product Timing, which cautions against using business-model category to predict second-product timing even though it clearly does predict first-product PMF timing.