They are not really competitors. They solve different jobs.
- Canva is for fast marketing graphics: social posts, flyers, presentations, documents. You start from a template and finish in minutes.
- Figma is for designing products: app screens, websites, components, design systems, and clickable prototypes that developers build from.
If you want a career in UI/UX or product design, learn Figma. If you need a good-looking post by this evening and design is not your job, use Canva. Many designers use both, for different work.