Reportedly, prototypes of this year's foldables are apparently already in Samsung's headquarters, including what will become the Galaxy Z Fold4. According to two leakers who claim to have insider information on the upcoming handset, the Galaxy Z Fold4 could launch with a new display format and a superior under-display camera compared to the Galaxy Z Fold3.
https://www.notebookcheck.net/Samsung-Galaxy-Z-Fold4-prototypes-New-display-format-and-a-greatly-improved-under-display-camera-tipped-to-be-making-their-way-to-Galaxy-Z-Fold3-successor.598457.0.html