I just updated org-mode using package.el and got release 9.5.3

Now I get an error in org-at-timestamp-p (OATP), which is invoked when calling org-agenda.

I checked the repository and the problem is in commit 1f617727f1, which added to this function the following code block:

-  (let* ((regexp (if extended
-                     (if (eq extended 'agenda)
-                         org-element--timestamp-regexp
-		       org-ts-regexp3)
-                   org-ts-regexp2))
+  (let* ((regexp
+          (if extended
+              (if (eq extended 'agenda)
+                  (rx (or (regexp org-ts-regexp3)
+                          (regexp org-element--timestamp-regexp)))
+		org-ts-regexp3)
+            org-ts-regexp2))

The issue arises where OATP uses rx to process a regex stored in org-ts-regexp3:

(rx (or (regexp org-ts-regexp3) ; here
        (regexp org-element--timestamp-regexp)))

This fails because rx-check checks the sub-expression (regexp org-ts-regexp3) to make sure that org-ts-regexp3 is a string, but org-ts-regexp3 is not evaluated, and the symbol org-ts-regexp3 is not a string (it's a symbol), even though it's value is a string.

I'm not sure whether this is a bug in org-mode proper (I would have thought this would be caught before release) or perhaps org-mode expects some version of rx.el that I do not have. Unfortunately, I don't see a version number in rx.el, only a copyright date.

I am running Emacs 25 (Aquamacs). So, maybe this code requires Emacs 26? If so, it would be nice if org-mode 9.5.3 was tagged as incompatible with Emacs 25? (It would also be nice if package mode supported roll-back, but that's OT here!)