Several bean plants on the west side of my garden started having these brown spots on the leaves. We never had any issues in the past until this year. There are no issues with any of the bean plants on the other side of the garden.
It is quite a concern to have these brown spots on the leaves of your bean plants. Fortunately Toronto Master Gardeners have answered a question similar to yours. You may find the link below helpful.
Good luck in dealing with the beans plants with the brown spots. May the other bean plants on the other side of your garden remain healthy.