Yoga originated as meditative practice in Hinduism with some spiritual goals that are a bit more than just the more generic “mindfulness” you might find in your typical modern fitness class.

(It’s also found in Buddhism and Jainism,)

The physical stretches and poses are great for healthy, low intensity exercise; and meditation is a thing that exists basically in every religious flavor you’d like; so it’s certainly possible to make even a “fundie-approved” version, but eh. Good luck with that.

Ultimately it could have been lumped into “other beliefs”,