It does nmap some of c* key sequences,
however, there exists c{motion} vim key binding.

For example, in the case of below,
it prevents vim default key binding.

//   Cursor is here
//   *
some_function_foo_bar();
//   ^^^^^^^^
//   On `ct_`, it had deleted here and started insert mode;
//   however, now `conflict-marker.vim` binds over the key sequence
//   (i.e. `ct`, `@<Plug>(conflict-marker-themselves)`).

The key mappings are only for the buffer that is detected conflict.
But once the mappings are activated, they remain until the buffer is wiped out (i.e. :bw).

I know there exists g:conflict_marker_enable_mappings option to skip the key mapping.
But I think you shouldn't overwrite such commonly used key binding.