Thank you for your advice and for looking into this!

I went through all the hooks, they just start:

org-superstar-mode
prettify-symbols-alist
org-auto-tangle-mode
typo-mode

But I commented out almost everything in my config and found out it has to do with mixed-pitch. The solution:

  (use-package mixed-pitch
    :config
    (setq mixed-pitch-variable-pitch-cursor 'box))

When no setting is done, mixed-pitch automatically sets the cursor to 'bar. So my setting it to 'box by cursor-type was of no use for my org-mode buffers (with mixed-pitch). Phew! Now it works as I like it.

Thanks again for your quick answer. It’s great that everything can be set to one’s liking in Emacs.

Thank you for the summary of your last meeting, I learned about cool packages I didn’t know about.