Samsung is tipped to equip the Galaxy Z Fold4 with an S-Pen slot accompanied by a new, thinner stylus to fit into the phone's slim chassis. That new S-Pen now looks to have entered production, four months away from the Galaxy Z Fold4's expected debut.
https://www.notebookcheck.net/Samsung-Galaxy-Z-Fold4-New-S-Pen-production-begins-ahead-of-launch.614348.0.html