Seems to be you have selected the incorrect “light logo” for the mobile view. As I inspected code and noticed that the “light logo” is actually the dark one! Replace that logo with white one and it should be just fine.
And if you don’t want to play around with the theme setting, Just go to wp-admin > Appearance > Customizer > Custom CSS and add below and save it.
@media(max-width: 1199px) {
body.switchable-logo header#header .menuzord-brand .logo-light.logo-1x {
display: none;
}
body.switchable-logo header#header .menuzord-brand .logo-dark.logo-2x.retina {
display: block;
}
}