Volume change delayed until the popup fades
I've noticed that when adjusting the sound, the actual sound level isnt changed until the dialogue fades. This means that pressing volume up doesn't have an immediate reaction. If you press volume up several times quickly because its still quiet, it will be a lot louder then you intended when the dialogue fades and the volume is finally changed.
Interestingly, I tried to film this behavior with pavucontrol open so it was very clear what was happening, but the volume does change instantly when pavucontrol is open.