Seems the insert-heading-issue is still struggling, this time during a "make check" @ d5ee33fed8dd80d3f9f9811d86a73827fde80780 using Emacs 29:
Test test-org/insert-heading condition: (ert-test-failed ((should (equal "* 1\n** 1.1\n** 1.2\n*\n* 2" (org-test-with-temp-text "<point>* 1\n** 1.1\n** 1.2\n* 2" ... ...))) :form (equal "* 1\n** 1.1\n** 1.2\n*\n* 2" #("* 1\n** 1.1\n** 1.2\n* \n* 2" 0 2 (face org-level-1) 2 3 (face org-level-1) 4 5 (face org-level-2) 5 7 (face org-level-2) 7 10 (face org-level-2) 11 12 (face org-level-2) 12 14 (face org-level-2) 14 17 (face org-level-2) 21 23 (face org-level-1) 23 24 (face org-level-1))) :value nil :explanation (arrays-of-different-length 23 24 "* 1\n** 1.1\n** 1.2\n*\n* 2" #("* 1\n** 1.1\n** 1.2\n* \n* 2" 0 2 (face org-level-1) 2 3 (face org-level-1) 4 5 (face org-level-2) 5 7 (face org-level-2) 7 10 (face org-level-2) 11 12 (face org-level-2) 12 14 (face org-level-2) 14 17 (face org-level-2) 21 23 (face org-level-1) 23 24 (face org-level-1)) first-mismatch-at 19))) FAILED 998/1094 test-org/insert-heading (0.018306 sec) at ../lisp/test-org.el:1845