SFTPPlus version 3.13.1 was release as a bugfix release on top of 3.13.0.

It includes a security fix in which the transfer scripts were previously executed a root, even if the process was configured to run under a non-root account.

If possible we recommend upgrading to version 3.16.0 as the security fix is also included in that version, together with many other new functionalities and minor bug fixes.

You can check the full release notes.