No sound on WhatsApp status in silent mode but youtube or other apps have sound...shouldn't it be consistent

Put mobile on silent mode. Now go to whatsapp status no sound..try to press volume keys still no works..though the animation shows its increasing and decreasing..but no sound.

Once you turn off silent mode it works. But this seems a bug.. As its media and should be having sound as like other apps have sound in silent mode for example youtube..appleTV.. Not sure why apple team is making life difficult..Just to listen WhatsApp status need to switch there modes..from silent to ring mode.