Notification freezing application

Hello everyone. I've gotten some problem since September update, and upgrading to 20.04 did not solve the problem at all. Each time I received a notification, it makes the application that sent it freeze for about 1 minute, the most annoying being Skype and alarm-clock-applet since I use them for working. Have anyone encountered a problem like that ? It seems it come from the daemon, but I have no idea about how to correct it.

Any help would be much appreciated, thanks you.