electric-indent-mode is enabled by default.
You can turn it off via (electric-indent-mode -1) in your ~/.emacs, but if you want to only disable it for a particular char (e.g. () in a particular major mode, the normal way could look like:
(delq ?\( ...
C-hk( tells us:
( runs the command c-electric-paren (found in c-mode-map), which
is an interactive compiled Lisp function in ‘cc-cmds.el’.
It is bound to ), (.
(define-key c-mode-map (kbd "(") #'self-insert-command)
(define-key c-mode-map (kbd ")") #'self-insert-command))