Hi Anne,
The Watchdog Window Period is configurable by SW. Not only during the INIT_FS phase (first 256ms after RSTB is released), but also later during the Normal mode.
By default, WD Window duration is 3ms which is in alignment with an FTTI below 10ms.

The Watchdog Window Duty Cycle is set to 50% ±10% and is not modifiable.

Best regards,
Tomas