Plugin breaks key mapping

[fvisin]

cmp-buffer breaks this mapping:

:nnoremap <Space> i_<Esc>r|                     " Insert single char in normal mode with space + char

Specifically, pressing "" results in "__" being inserted instead of a single space " ".

I am not sure why this happens, but it looks like the same issue happens if I load any of these:

cmp-nvim-lsp
cmp-path

Happy to help testing ideas if that's useful!

[tribela]

cmp-cmdline also causes problem