I feel like the one big thing is just how majorly obvious it makes how many digits/characters the code you’re looking for is. You see the big four boxes, you get a text message or email that has four digits in it, you know you’re probably looking at the right thing.

I ain’t necessarily advocating for it, but that’s the rub.

Just take one field. If you know it will be numeric, then apply a regex pattern to the text input. Then upon the correct sequence being entered, just auto-submit the form.

Your solution looks cleaner to me