Filekind uses heic-to 1.5.2 (Hopper Gee), distributed under LGPL-3.0-or-later.
The unmodified CSP ES module is supplied separately as /vendor/heic-to.js.
It includes libheif 1.22.2 (struktur AG, LGPL-3.0-or-later) and libde265
1.0.16 (struktur AG, LGPL-3.0-or-later). License texts and corresponding
source archives are provided beside this notice in /vendor/sources/.

You may inspect, replace, modify, and reverse-engineer these library
components for debugging modifications under their license terms.
Replace static/vendor/heic-to.js with a compatible CSP module and rebuild
to use a modified library. Filekind imports it dynamically by that URL;
it is not linked into the application JavaScript bundle.

Sources and build instructions:
https://github.com/hoppergee/heic-to/tree/v1.5.2
https://github.com/strukturag/libheif/tree/v1.22.2
https://github.com/strukturag/libde265/tree/v1.0.16
The heic-to source archive includes esbuild.mjs and the CSP libheif JS.
Its README documents the Emscripten build with USE_UNSAFE_EVAL=0 USE_WASM=0.

Local source downloads:
/vendor/sources/heic-to-1.5.2.tgz
/vendor/sources/libheif-1.22.2.tar.gz
/vendor/sources/libde265-1.0.16.tar.gz
/vendor/HEIC-TO-LICENSE.txt
/vendor/GPL-3.0.txt