According to reports, Samsung has no plans to bring in-display or ultrasonic fingerprint scanners to next-generation Galaxy Z devices. Instead, the Galaxy Z Fold4 and Galaxy Z Flip4 will maintain capacitive fingerprint scanners built into their power buttons.
https://www.notebookcheck.net/Next-generation-Samsung-Galaxy-Z-Fold-and-Galaxy-Z-Flip-devices-to-stick-with-existing-biometric-security-methods.612900.0.html