Becoming a yoga teacher for free in current generation is definitely possible, especially if you a resourceful and willing to do some extra effort you can become a yoga teacher for free or at very low-cost with some dedication.
there's some step-guidance to help you to become a yoga teacher for free:

Step 1: Develop a strong yoga skill and practice

• First, Find free online classes:- Find a suitable free online yoga classes and workshop, which will help you in developing the yoga skills and practice.
• Practice Regularly:- Commit to practice yoga regularly, if you are willing to become a yoga teacher or expert, as practicing yoga regularly can deepen your understanding and improve your skills.

Step 2: Learn about yoga Teaching

• Watch YouTube Videos:- Find a good YouTube channel that will provide you better tutorials that will demonstrate yoga teaching techniques.
• Reading Yoga Books:- Read books and articles about teaching methodology and yoga philosophy.

Step 3: Find a Mentor

• Find a mentor:- Search for an experienced yoga teacher and aske them if they would mentor you or guide you.
• Join Online Yoga community:- Join online yoga communities, from where you will get to meet other yogis and you can learn from their experience and perspective.

Step 4: Gain Teaching Experience

• Volunteer:- Volunteer to gain some teaching skills and experience both for a successful yoga teaching career.
• Teach some of yoga student at small yoga centers:- Try joining any small yoga centers to gain some experience in yoga for a better career.

Step 5: Build your Brand

• Create a social media profile:- Create a strong social media profile to connect with potential students and promote your yoga teaching services.
• Build Network:- Build a strong network with other yoga teachers, build relationship and find opportunity.

Conclusion:
Becoming a yoga teacher for free needs hard work and passion for yoga and consistency towards your aim you can develop your skills, have experience and build a strong career in yoga teaching without spending a-lot.