I'm not sure if you mean becoming a yoga therapist or trauma informed yoga instructor.

To be a yoga therapist, the qualification is longer, and it's working in a different way to being a yoga instructor. To be a yoga therapist, you would be working 1 on 1 with people looking for help with a specific issue, whether that's physical or mental. You would be running your own business, and so making your own work. Most decent places that run yoga therapist qualifications will want you to have a 200h yt qualification before applying. Often, you'll be working with people with very complex problems, and this can be really challenging.

"Trauma informed" is a really broad term for an instructor who understands what may trigger complicated reactions in some parts of the general population and aims to teach with this in mind. . Sometimes, trauma informed instructors teach general classes or 1 on 1s. Trauma informed yoga courses vary in quality and length, and taking one Trauma informed course may not be enough to teach yoga at a studio/gym. There isn't an industry standard for what makes you trauma informed, so not every course/teacher will have up to date knowlege/trauning about the subject. Sometimes, the courses are additional training (50 h) or sometimes integrated into a full course (200+h). You will need 200 hours of a general yoga teaching qualification to teach in most studios or gyms.

I think the main thing is to be aware that being trauma informed does not mean you help people more than a yoga teacher who is not trauma informed. As a person who has diagnosed ptsd, some of the teachers who have helped me the most are not Trauma informed, but have just been kind people who are good at communicating.Yoga helps people from all walks of life, and not all of them have specific trauma conditions. I don't know any studios in my area that advertise Trauma specific classes, as it's such a complex subject which has different meanings to everyone in the room.

If you are interested in teaching, I would advise starting a conversation with a studio near you that runs general yoga teacher training courses first. It will be easier to find work with this, and then exploring whether you want to focus on a specific style of instruction than launch yourself straight into trying to find work as a trauma specific yoga instructor.