No. EPA's guidance for buyers and sellers says that where radon problems have been fixed, home sales have not been blocked, and that saved test results and records of the fix can be a positive selling point. The post-mitigation test is what a buyer will ask to see.
More detail
What is documented is the paper trail, not a price premium. EPA's Home Buyer's and Seller's Guide recommends testing before a home goes on the market and fixing a high result then, since the seller has more time to deal with it before a buyer is involved, and it advises buyers to ask for the seller's test results and any information about an installed system. A buyer may still ask for a new test if the last one was not done correctly, is not recent, for example within two years, predates renovations, or was taken on a higher floor than the buyer plans to use. In Ohio, the residential property disclosure form prescribed under ORC 5302.30 lists radon gas among the hazardous materials a seller discloses within actual knowledge. A system installed by an Ohio licensee under the Ohio Radon Mitigation Standards comes with an information package covering the floor-plan drawing, pre- and post-mitigation test data, contracts and warranties, a description of the system, and operating instructions, and the finished drawing is available to any future owner on request. When a buyer's test comes back high and no system exists, EPA says buyer and seller should discuss the timing and cost of the fix, and its guide suggests the contract spell out when mitigation will happen and who pays. Keep the post-mitigation report and any later retests together, and see our radon disclosure answer and real estate radon services for the sale itself.