Security

Diagram text. Pele escapes diagram text, filters links and styles, and limits source and output size. Read Pele's security page before rendering diagrams you did not write. pele-animate does not weaken any of that: it reads the SVG after Pele renders it.
Pins. The %% pa: comment is parsed with a simple pattern (step numbers and ids). It cannot run code.
Glyph markup is trusted. registerGlyphs() and registerTabler() insert your markup into the page as SVG. Register only markup you wrote or reviewed. The bundled Tabler and doverunner-* packs are static files in the package.
No network. pele-animate makes no requests and loads no remote assets.
No eval. Nothing in the package uses eval or generates code, so a content security policy without unsafe-eval works.

Report a vulnerability by opening an issue on the GitHub repository that asks for a private contact. Leave the details out of the public issue.