If you read the problems with Big Sur, you may realize that the problem is with the new Big Sur macOS. Intuit can only do so much to make it work with the new Big Sur OS. Some users appear to have succeeded using TurboTax under Big Sur, and many have not. I have given up on TT working under Big Sur at this time, and will be going back to macOS Catalina. I have a number of other system problems that the upgrade to Big Sur have created. You may want to read the terms of usage from both Apple and Intuit before spending time on a formal complaint. What ever you do, Good Luck. You are not alone in your frustration.
