The CODE tag is supposed to be rendered in a monospace font and keep all whitespace intact, intended for use when showing programming source where indentation makes things easier to read (and in a language like Python is actually semantically important), and still useful on non-programming sites like FlyerTalk for showing data in tabular form, maybe with columns of words/numbers aligned, for example:

but if you create a post with aligned text in a CODE block, then you edit the post, then whitespace is deleted and it ends up looking like this:

(this can also be reproduced even without editing an existing post -- start a new post, click "Source" to switch from the WYSIWIG editor into the raw source editor mode, carefully compose a CODE table with specific whitespace layout, and then click "Source" again to go back to the visual mode, it also destroys white space.)