How can I unmap <esc> key in vim, it keeps reverting despite setting it in .vimrc?

Question

Hi I am having some issue trying to unmap this key in my .vimrc. I've tried a lot of suggestions and remapping but it seems to be resetting itself every time.

unamp <Esc> 
unmap! <Esc>
map <Esc>^[ <Esc>^[
map <Esc> <Nop>

Everytime I open a file in vim and type the following in command mode:

:map <Esc>

The following shows up and I want to get rid of the n <Esc> *:bprevious<CR> mapping completely, that is not in my .vimrc file but it keeps resetting.

n <Esc>     * :bprevious<CR>
  <Esc>^[     <Esc>^[
ov <Esc>      <Nop>

The out from the command suggested in the comment:

:verbose :map <Esc>

Result:

n  <Esc>     * :bprevious<CR>
       Last set from ~/.vimrc
   <Esc>^[   [Esc]^[
       Last set from ~/.vimrc
ov <Esc>     <Nop>
   Last set from ~/.vimrc 

I've checked my .vimrc and I definitely don't have it set.

Answer 1

Ctrl-[ is the the same as ESC, as mentioned in :help <Esc>:

notation    meaning         equivalent  decimal value(s)    ~
-----------------------------------------------------------------------
<Nul>       zero            CTRL-@    0 (stored as 10) *<Nul>*
<BS>        backspace       CTRL-H    8 *backspace*
<Tab>       tab         CTRL-I    9 *tab* *Tab*
                            *linefeed*
<NL>        linefeed        CTRL-J   10 (used for <Nul>)
<FF>        formfeed        CTRL-L   12 *formfeed*
<CR>        carriage return     CTRL-M   13 *carriage-return*
<Return>    same as <CR>                *<Return>*
<Enter>     same as <CR>                *<Enter>*
<Esc>       escape          CTRL-[   27 *escape* *<Esc>*

Answer 2

I think I found the 'potentially' culprit. I would love an explanation if anyone can explain it.

These two lines when I comment them out the first entry gets erased.

nnoremap <C-]> :bnext<CR>
nnoremap <C-[> :bprevious<CR>

I'm not sure why that would affect the <Esc> key but it seems to have 'fixed' the issue.