I don't think there's an easy way out for this one. You might do something like:

(add-hook 'type-mode-hook
          (lambda ()
            (when (and type-mode (derived-mode-p 'markdown-mode))
              (let ((map (make-sparse-keymap)))
                (set-keymap-parent map type-mode-map)
                (define-key map (kbd "`") 'self-insert-command)
                (push `(type-mode . ,map)
                      minor-mode-overriding-map-alist)))))

                

I don't think there's an easy way out for this one. You might do something like:

(add-hook 'typo-mode-hook
          (lambda ()
            (when (and typo-mode (derived-mode-p 'markdown-mode))
              (let ((map (make-sparse-keymap)))
                (set-keymap-parent map typo-mode-map)
                (define-key map (kbd "`") 'self-insert-command)
                (push `(typo-mode . ,map)
                      minor-mode-overriding-map-alist)))))