Brave browser and Vivaldi won't open in KDE

 Ran into a weird issue today - suddenly Brave and Vivaldi refuse to open.  Same for Brave Beta.  Running from the command line I see something like this

[15524:15524:0724/100844.416388:ERROR:process_singleton_posix.cc(226)]
read() failed: Connection reset by peer (104)
[15524:15524:0724/100844.550935:ERROR:browser_main_loop.cc(278)]
GLib-GObject: g_type_add_interface_static: assertion 'G_TYPE_IS_INSTANTIATABLE (instance_type)' failed
[15524:15524:0724/100844.550956:ERROR:browser_main_loop.cc(278)]
GLib-GObject: g_type_interface_add_prerequisite: assertion 'G_TYPE_IS_INTERFACE (interface_type)' failed
[15524:15524:0724/100844.550963:ERROR:browser_main_loop.cc(278)]
GLib: g_once_init_leave: assertion 'result != 0' failed
[15524:15524:0724/100844.550966:ERROR:browser_main_loop.cc(278)]
GLib-GObject: g_type_add_interface_static: assertion 'G_TYPE_IS_INSTANTIATABLE (instance_type)' failed
[15524:15524:0724/100844.550969:ERROR:browser_main_loop.cc(278)]
GLib-GObject: g_type_register_static: assertion 'parent_type > 0' failed

I fixed this by chance by going into the KDE settings > Appearance and changing everything back to Breeze.  And under 'Application Style' on the bottom right I clicked 'Configure GNOME/GTK Application Style' and changed that to Breeze (it was blank before).  Did not have to reboot and all browsers launch ok now.  Did have a slight delay with Vivaldi but it seems ok.