PDF.js 4.10.38 embeds OpenJPEG 2.5.3 and the Mozilla pdf.js.openjpeg wrapper
as WebAssembly within pdf.worker.min.mjs. No separate WASM download is used.

OpenJPEG 2.5.3: BSD-2-Clause
Copyright holders and full terms: OPENJPEG-LICENSE.txt
Source and license: https://github.com/uclouvain/openjpeg/tree/v2.5.3
https://github.com/uclouvain/openjpeg/blob/v2.5.3/LICENSE

Mozilla pdf.js.openjpeg wrapper: BSD-2-Clause
Copyright (c) 2024, Mozilla Foundation
Full terms: PDFJS-OPENJPEG-LICENSE.txt
License source at the revision current when PDF.js updated to OpenJPEG 2.5.3:
https://github.com/mozilla/pdf.js.openjpeg/blob/154e3b397c5b4f22d4f93e3cd8bacde090d6e453/LICENSE

PDF.js version-pinned provenance:
https://github.com/mozilla/pdf.js/blob/v4.10.38/external/openjpeg/README.md
https://github.com/mozilla/pdf.js/blob/v4.10.38/external/openjpeg/openjpeg.js
https://github.com/mozilla/pdf.js/commit/19ea64c6d747bdb4aba6e3be751f193d5d312e0d
(The last commit updates OpenJPEG to 2.5.3.)

The embedded WASM is byte-identical to the payload in that PDF.js tag:
Size: 260821 bytes
SHA-256: f42cf36b55b433f16cb0ad57a2e54d98632834d67027bf28dfc561e3a18ea446

PDF.js distribution files are unmodified official pdfjs-dist 4.10.38 build files.
The BSD notices supplement the separately included Apache-2.0 license for PDF.js.