Notice
SVGO v3.3.0, which was meant to migrate to ESM without breaking CJS support, unfortunately broke CJS projects. There was a mistake with exports, so the loadConfig function wasn't available in the CJS bundle and lead to issues for many users.
Thanks to everyone who raised the issue, and to @nuintun who submitted a pull request to resolve it so quickly.
I apologize for letting that breaking change through, and will aim to do better. Namely, by adding more tests to cover our exports, and any other public interface in general for each distribution of SVGO, so this doesn't happen again.
SVGO v3.3.1 should resolve the issue for CJS projects, but if you encounter anything else, do let us know by opening an issue on GitHub.