There is a common dangerous Ruby Array situation when removing/deleting element from Array

a = [1, 2, 3 ]
b  = a
b.delete(2)

b
#=> [1, 3]

a
#=> [1, 3] ```

Full explanation why is posted in this article

Solution

a = [1,2,3]
b = a.dup
b.delete(2)

b
# => [1, 3]

a
# => [1, 2, 3]

https://blog.eq8.eu/til/remove-element-from-ruby-array-issue.html