Some browser notifications are not being hidden after the delay.

For example, whatsapp notifications stays on but if 2 notifications from whatsapp come one after another, only the first one is kept. So weird!

I removed all the KDE config and started over and it worked for a few days, then it showed up again.

I googled a lot, used the new KDE matrix chat but no response and seems is very specific to my setup.

What is the best way to debug this? I am a developer (not C but Javascript/PHP) so I dare to go deep as this is really annoying.

thanks for any pointers!