Normally I don't type lines like that!
But what you are seeing is the classic staircase effect.
It is caused by having the autoindent feature set for busybox vi. It is on by default.
So when you want to paste text with existing indentation and want to avoid the "staircase" effect, just issue
:set noautoindentBefore you paste and reenable with
set autoindentCaution when using nano for possible word wrap which will break long lines, a code killer.