I'm seeing lot of these:
Code:
gnome-panel[2799]: gtk_widget_size_allocate(): attempt to underallocate GtkMenuBar's child GtkMenuItem 0x55f712bd64d0. Allocation is 161x24, but minimum required size is 161x29.
Repeat this line with different contents where coloured.
I guess I'll experience glitches like these during the Gnome 3.28 to 3.30 transition period. And yes, I've got proposed enabled.