Please provide mode details about what you tried.

OK, I will try. I start emacs with

emacs -Q -l emacs_init/minimal-org.el

Here, minimal-org.el has the following contents:

;; Activate debugging.
(setq debug-on-error t
  debug-on-signal nil
  debug-on-quit nil
  icalendar-export-sexp-enumeration-days 400)

;; Add latest Org mode to load path.
(custom-set-variables
 '(package-selected-packages
   '(org-plus-contrib)))

In this setup, M-x version and M-x org-version bring up the following information:

GNU Emacs 28.2 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.20, cairo version 1.16.0) of 2023-06-23

Org mode version 9.5.5 (release_9.5.5 @ /snap/emacs/current/usr/share/emacs/28.2/lisp/org/)

org-time-stamp gives <2023-07-24 Mo>.

I create a minimal org-file test.org with the following contents:

* Test 1  
%%(org-anniversary 2022 07 23) Test1  
* Test 2  
%%(org-anniversary 2022 07 25) Test2 %d

I open this file in emacs and hit C-c C-e c f to export it to icalendar. The file test.ics has the following contents:

BEGIN:VCALENDAR
VERSION:2.0
X-WR-CALNAME:test
PRODID:-//Marcus//Emacs with Org mode//EN
X-WR-TIMEZONE:CEST
X-WR-CALDESC:
CALSCALE:GREGORIAN
END:VCALENDAR