A critical vulnerability was recently discovered related to systems/software that run Apache Log4j
More information about this vulnerability can be found here. National Vulnerability Ddatabase - CVE-2021-44228 (nist.gov)
This is an industry-wide vulnerability affecting the Apache Log4j itself and is not specific to Binary Tree Archive Migrator.
Binary Tree Archive Migrator for Notes does not use Apache Log4j, therefore is not affected by CVE-2021-44228