Nikon D780 DSLR Camera (Body Only) - Manual (Page 373)

327 Other Shooting Options
D When [On] Is Selected for [Silent Photography]
Selecting [ On ] for [ Silent photography ] disables some camera features,
including:
• ISO sensitivities of Hi 0.3 through Hi 2
• Flash photography
• Exposure delay mode
• Long exposure noise reduction
• Flicker reduction