Concat is AGPL-3.0-or-later, with a plugin exception for Concat API
plugins (LICENSE-EXCEPTIONS.md).
The installers bundle GPL-built FFmpeg binaries, invoked as separate
programs, and statically link GPL-3.0 espeak-ng — sources and licenses
in THIRD_PARTY_NOTICES.md.
Full Changelog: v0.2.0-alpha.19...v0.2.0-alpha.20