Rescheduling repeating todos in org mode without breaking regular schedule

config.el

(defun iko/org-is-static-repeater ()
  ;; Is this a repeater that uses the current date for rescheduling (.+) or
  ;; a „static“ repeater that uses the last scheduled date (++)?
  (when-let ((repeater (org-get-repeat)))
    (not (string-prefix-p ".+" repeater))))

(defun iko/org-entry-put-nil (EPOM PROPERTY VALUE)
  (and VALUE (org-entry-put EPOM PROPERTY VALUE)))

(defun iko/org-ts-inactive→active (text)
  (when (and text (string-match "\\[\\(.+\\)\\]" text))
    (concat "<" (match-string 1 text) ">")))

(defun iko/org-ts-active→inactive (text)
  (when (and text (string-match "<\\(.+\\)>" text))
    (concat "[" (match-string 1 text) "]")))

(advice-add
 'org-todo
 :around
 (defun iko/org-todo-schedule-fix (oldfun &rest r)
   (if (iko/org-is-static-repeater)
       (let ((prev-scheduled-stamp (org-entry-get nil "SCHEDULED"))
             (prev-deadline-stamp (org-entry-get nil "DEADLINE"))
             ;; The original timestamps are stored as inactive timestamps
             (orig-scheduled-stamp (iko/org-ts-inactive→active (org-entry-get nil "ORIG_SCHEDULED")))
             (orig-deadline-stamp (iko/org-ts-inactive→active (org-entry-get nil "ORIG_DEADLINE"))))
         (iko/org-entry-put-nil nil "SCHEDULED" (or orig-scheduled-stamp prev-scheduled-stamp))
         (iko/org-entry-put-nil nil "DEADLINE" (or orig-deadline-stamp prev-deadline-stamp))
         (unwind-protect
             (apply oldfun r)
           (let ((next-scheduled-stamp (org-entry-get nil "SCHEDULED"))
                 (next-deadline-stamp (org-entry-get nil "DEADLINE")))
             (if (equal orig-scheduled-stamp next-scheduled-stamp)
                 (iko/org-entry-put-nil nil "SCHEDULED" prev-scheduled-stamp)
               (iko/org-entry-put-nil nil "ORIG_SCHEDULED"
                                      (iko/org-ts-active→inactive next-scheduled-stamp)))
             (if (equal orig-deadline-stamp next-deadline-stamp)
                 (iko/org-entry-put-nil nil "DEADLINE" prev-deadline-stamp)
               (iko/org-entry-put-nil nil "ORIG_DEADLINE"
                                      (iko/org-ts-active→inactive next-deadline-stamp))))))
     (apply oldfun r))))

(advice-add
 'org-schedule
 :before
 (defun iko/org-schedule-schedule-fix (&rest r)
   (when (and (iko/org-is-static-repeater)
              (not (org-entry-get nil "ORIG_SCHEDULED")))
     (iko/org-entry-put-nil nil "ORIG_SCHEDULED" (org-entry-get nil "SCHEDULED")))))


(advice-add
 'org-deadline
 :before
 (defun iko/org-deadline-schedule-fix (&rest r)
   (when (and (iko/org-is-static-repeater)
              (not (org-entry-get nil "ORIG_DEADLINE")))
     (iko/org-entry-put-nil nil "ORIG_DEADLINE" (org-entry-get nil "DEADLINE")))))

See also https://valentin-herrmann.de/p/rescheduling-repeating-todos-in-org-mode-without-breaking-regular-schedule/.