There does appear to be some licensing awkwardness here. The license is nominally GPLv3, but it says it is based on AGPLv3 projects. It also appears to misidentify (it may have been correct at the time) PyMuPDF as GPLv3 when that appears to actually be AGPLv3. My assumption is that using this would require complying with AGPLv3?

There's the additional oddity that a portion of the repository (the recipes directory) is licensed under CC-BY-NC-SA, and so the repository is not fully open source. This is particularly confusing, however, as the functional content of the recipes directory appears to be mostly records of direct observations of parameter choices in external documents and tools, and so doesn't seem like it would be copyrightable at all, at least in the US.