Advanced media dialog is shown with horizontal scrollbars because button labels don't fit.
|mediawiki/extensions/VisualEditor : master||ve.ui.MWMediaDialog: Use dropdown for image type selector|
Well, given that we're replacing this dialog with a new design which will be wider (as we'll have now drawer), and it's only in the "advanced" section, it's maybe not worth worrying for now? Eh.
Reciting myself from T190462:
No regression to my knowledge. We once discussed a compromise as solution in T112982 with Ed being against the proposal. We'd need a constructive idea…
I was hoping for inputs by @Esanders – if spilling one button on next line seems insufficient, how about calculating the available horizontal size and putting all of them underneath each other when above?