As bean plants go that doesn't look life threatening. I'm not sure what caused the damage but as long as it doesn't spread then the plants should do fine. The lowest leaves almost always suffer from early damage from pests, disease or even shading but plants can out run minor damage with new growth.

Those look fine to me. Not picture-perfect, but fine.

This has some good pics of sunscald on bean leaves..I think that's what that is

https://plantvillage.psu.edu/posts/4359-bean-what-is-going-on-with-my-bean-plants

This looks a lot like the leaf damage to some pole beans I have growing in my glass greenhouse. Definitely makes sense that the leaves got a bit scorched. Donna R, thanks for the link!