HEIC decoding uses heic-to 1.5.2 (Hopper Gee), licensed LGPL-3.0-or-later.
It is loaded as a separate optional module. The application does not modify the decoder.
The unmodified npm source distribution and build instructions are available beside this notice:
heic-to-1.5.2.tgz, HEIC-BUILD.md, HEIC-LICENSE.txt.
Upstream: https://github.com/hoppergee/heic-to
Underlying libheif release: https://github.com/strukturag/libheif/releases/tag/v1.22.2
To replace the decoder, use its documented heicTo API in src/images.ts and rebuild with npm run build.