bug#43069: 28.0.50; Org-mode does not Render Sub- and Superscripts in text with italics

[Arthur Miller]

As title says, when in org-mode, sub- and superscripts are not rendered pretty
when italics property is also specified (togeteher with
org-toggle-pretty-entities). There is a SX question about 3 years old on
same subject:

https://emacs.stackexchange.com/questions/31149/superscript-or-subscript-inside-italics-in-org-buffer-does-not-change-text-app

but anything said there seem to help.

Steps to reproduce:

1. start Emacs with -Q
2. C-x C-f test.org
3. Enter expresion: (f^*,(LAMBDA,(x_1^*,...,x_n^*),e^*))
4. C-c C-x \ to activate pretty-printing of symbols
   Subscripts and superscripts are now rendered nicely and properly.

5. Surround the expression with '/': /(f^*,(LAMBDA,(x_1^*,...,x_n^*),e^*))/
   The text will not be italicized unless there is a space and *something*
   before last '/', for example: /(f^*,(LAMBDA,(x_1^*,...,x_n^*),e^*)) ./
   Text is now rendered in italics, but sub- and superscripts are
   rendered as plain text, not as utf8.
   
In GNU Emacs 28.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.22, cairo 
version 1.17.3)
 of 2020-08-26 built on pascal
Repository revision: aa526c9470d679e9144af55d9e56928a111d2ceb
Repository branch: feature/native-comp
Windowing system distributor 'The X.Org Foundation', version 11.0.12009000
System Description: Arch Linux

Configured features:
XPM JPEG TIFF GIF PNG RSVG CAIRO SOUND GPM DBUS GSETTINGS GLIB NOTIFY
INOTIFY ACL GNUTLS LIBXML2 FREETYPE HARFBUZZ M17N_FLT LIBOTF ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 XDBE XIM MODULES THREADS LIBSYSTEMD JSON
PDUMPER LCMS2

Important settings:
  value of $LANG: sv_SE.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Org

Minor modes in effect:
  bug-reference-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug sendmail vc-git diff-mode bug-reference
org-element avl-tree generator ol-eww ol-rmail ol-mhe ol-irc ol-info
ol-gnus nnir gnus-sum url url-proxy url-privacy url-expand url-methods
url-history mailcap shr kinsoku url-cookie url-domsuf url-util url-parse
auth-source cl-seq eieio eieio-core cl-macs eieio-loaddefs json map
url-vars svg xml dom browse-url gnus-group gnus-undo gnus-start
gnus-cloud nnimap nnmail mail-source utf7 netrc nnoo parse-time iso8601
gnus-spec gnus-int gnus-range message rmc puny rfc822 mml mml-sec
password-cache epa derived epg epg-config mm-decode mm-bodies mm-encode
mail-parse rfc2231 mailabbrev gmm-utils mailheader gnus-win gnus
nnheader gnus-util rmail rmail-loaddefs rfc2047 rfc2045 ietf-drums
text-property-search seq byte-opt gv bytecomp byte-compile cconv
mail-utils mm-util mail-prsvr wid-edit ol-docview doc-view jka-compr
image-mode exif dired dired-loaddefs ol-bibtex bibtex ol-bbdb ol-w3m org
ob ob-tangle ob-ref ob-lob ob-table ob-exp org-macro org-footnote
org-src ob-comint org-pcomplete pcomplete comint ansi-color ring
org-list org-faces org-entities time-date subr-x noutline outline
easy-mmode org-version ob-emacs-lisp ob-core ob-eval org-table ol
org-keys org-compat advice org-macs org-loaddefs format-spec find-func
cal-menu easymenu calendar cal-loaddefs cl-loaddefs cl-lib time tooltip
eldoc electric uniquify ediff-hook vc-hooks lisp-float-type mwheel
term/x-win x-win term/common-win x-dnd tool-bar dnd fontset image
regexp-opt fringe tabulated-list replace newcomment text-mode elisp-mode
lisp-mode prog-mode register page tab-bar menu-bar rfn-eshadow isearch
timer select scroll-bar mouse jit-lock font-lock syntax facemenu
font-core term/tty-colors frame minibuffer cl-generic cham georgian
utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean
japanese eucjp-ms cp51932 hebrew greek romanian slovak czech european
ethiopic indian cyrillic chinese composite charscript charprop
case-table epa-hook jka-cmpr-hook help simple abbrev obarray
cl-preloaded nadvice loaddefs button faces cus-face macroexp files
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget hashtable-print-readable backquote threads dbusbind
inotify lcms2 dynamic-setting system-font-setting font-render-setting
cairo move-toolbar gtk x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 156465 9728)
 (symbols 48 18106 1)
 (strings 32 58986 2487)
 (string-bytes 1 1999116)
 (vectors 16 30202)
 (vector-slots 8 344717 11278)
 (floats 8 189 104)
 (intervals 56 281 0)
 (buffers 992 12))