Thank you, the patch fixed the problem.

сб, 26 апр. 2025 г. в 16:13, Eli Zaretskii <eliz@gnu.org>:

> > From: spl3g <spleefer6@gmail.com>
> > Date: Tue, 22 Apr 2025 11:22:26 +0300
> >
> > When enabling kill-ring-deindent-mode, it would replace spaces with tabs
> > in modes with indent-tabs-mode turned off.
> > It breaks some languages, that do not support tabs for example elm and
> > yaml.
> >
> > I think it is because the temp buffer it creates has indent-tabs-mode
> > turned on by default.
>
> Thank you for your report.  Does the patch below give good results?
>
> diff --git a/lisp/indent-aux.el b/lisp/indent-aux.el
> index 27d5875..ce98944 100644
> --- a/lisp/indent-aux.el
> +++ b/lisp/indent-aux.el
> @@ -45,10 +45,14 @@ kill-ring-deindent-buffer-substring-function
>            end (max a b)))
>    (let ((indentation (save-excursion (goto-char beg)
>                                       (current-column)))
> +        (i-t-m indent-tabs-mode)
>          (text (if delete
>                    (delete-and-extract-region beg end)
>                  (buffer-substring beg end))))
>      (with-temp-buffer
> +      ;; Indent/deindent the same as the major mode in the original
> +      ;; buffer.
> +      (setq indent-tabs-mode i-t-m)
>        (insert text)
>        (indent-rigidly (point-min) (point-max)
>                        (- indentation))
>