Array inside object not displaying correctly

I'm having an object of arrays. So I was trying to access one of the properties based on a randomly generated key but the result isn't accurate (Notice index 7 in the image below).

But when I try to access it without a randomly generated key, it displays correctly:

NOTE My original object looks Like this:

   const obj = {
      "25": [
               [{}, {}, {}, {}, {}],
               [{}, {}, {}, {}, {}],
               [{}, {}, {}, {}, {}],
            ],
      "26": [
               [{}, {}, {}, {}, {}],
               [{}, {}, {}, {}, {}],
               [{}, {}, {}, {}, {}],
            ],
      "27": [
               [{}, {}, {}, {}, {}],
               [{}, {}, {}, {}, {}],
               [{}, {}, {}, {}, {}],
            ],
      ...to "50"
   }

So, I was trying to access one of the keys based on a random number as mentioned above e.g obj[randomNumber], this didn't display correctly, but this obj[26] works.

What could cause this and how do I rectify it?

I'm ready to provide more explanations.