When a standard software program is installed, it often writes registry keys, temporary files, and user data to the system drive (usually C:). If the data you lost is on the C: drive, installing recovery software on top of it can potentially overwrite the very sectors where your deleted files reside, rendering them unrecoverable.
Verdict: Version 5.6.1 is for simple, FAT/NTFS, non-SSD recovery tasks. Modern version is for complex, encrypted, or NAS recovery. EASEUS Data Recovery Wizard Professional 5.6.1 Portable