Seems like the binary for MacOS still in 32 bit.

Multiple Operating System Support: TestDisk provides multi-language OS support, such as macOS, Windows, and different Linux and UNIX distributions. TestDisk has features for both novices and experts. This cause the binary failed to run since MacOS Catalina removing support for 32 bit application. Multiple Language Support: No data recovery tool is flawless If you face issues while recovering files with TestDisk, contacting its customer care executive is the only way out. For those who know little or nothing about data recovery techniques, TestDisk can be used to collect detailed information about a non-booting drive which can then be sent to a tech for further analysis. Partition table recovery using TestDisk is really easy. Those more familiar with such procedures should find TestDisk a handy tool in performing onsite recovery. Because we used sudo to launch testdisk, the recovered files have been restored with root as the owner. PhotoRec is a companion program for TestDisk. We can change the owner back to dave using chown: sudo chown dave.dave. We type the following to make sure the correct ownership has been restored: ls -l. It is designed to recover files including video, documents and archives from Hard Discs and CDRom and lost pictures from digital camera memory. TestDisk & PhotoRec for Mac OS X 7.0 - TestDisk is a powerful free data recovery software - offers free software downloads for Windows, Mac.

PhotoRec ignores the filesystem and goes after the underlying data, so it will still work even if your media's filesystem has been severely damaged or re-formatted.

Testdisk 32 bit