The issue was detected during working on packaging tlsh 4.13.3 for Debian.

Commit b54912c, Change default behaviour to output T1 at the start of the digest, lets Tlsh::getHash() return a different string than before. This can break code that, making use of tlsh as a shared library, calls Tlsh::getHash() without providing the showvers parameter.

Please release a 4.13.4 with this change reverted.