I think the code block seems to demonstrate a bug when another block is placed side by side to it, or maybe its is meant to be that way.
Below is the initial state
After dragging the bottom text block to be align side by side with the code block, notice that the code block is split into two. This is not what I expect.
I have sent this observation to the helpdesk, but currently no reply yet. So i raise it up here first, just in case.
Hopefully coda engineer can take this opportunity to revamp the code block as it lacks features that many users are requesting for (such as auto-highlighting syntax)