tight lats can also contribute to this.

This is called hyperkyphosis. The hunching can come from tiny fractures in your bones. Do you have osteoporosis?

If you do have osteoporosis or osteopenia, crunches and bending or twisting the spine are contraindicated. I stopped doing certain yoga poses and bending in order to prevent fractures.

More info: https://health.usnews.com/wellness/articles/older-adults-heres-what-causes-hunchback-and-how-to-prevent-it

If I had this issue, I'd be scheduling an appointment with a physical therapist. NovaCare has many good ones. I've seen an extremely stooped woman turn this around through exercise. She was a neighbor and the transformation was impressive.