Hello, I found the following weird behaviour. I first reported it to the spacemacs github (https://github.com/syl20bnr/spacemacs/issues/13901) but they confirmed that it is an upstream bug.

When I set some tasks to DONE and fold the headings with TAB, then when I cycle back from DONE to TODO it joins the next line with the current one.

Reproduction guide

• Make two TODO headings in org mode
  
• Cycle both TODO items to DONE
  
• Fold the headings (so the dots appear, because the timestamp gets folded with the heading)
  
• Cycle the first DONE heading
  

Observed behaviour:

The next line gets joined on the current one.

Expected behaviour:

No joining of lines.

System Info 

• OS: gnu/linux (WSL2, connected via X410 to Windows)
  
• Emacs: 28.0.50 (also tested it on 26.1, same behaviour observed)
  
• Graphic display: t
  
• Distribution: spacemacs
  
• Editing style: vim
  
• Completion: helm
  
• Layers:
  

(helm auto-completion emacs-lisp org themes-megapack treemacs)

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