Evolution mail client toolbar buttons too small

Hi Everyone,

with the latest update of Evolution the toolbar icons are too small for the display of my wifes new laptop

She owns a HP Elitebook 830 with 13.3" screen, but FullHD resolution (1920x1080).
Installed is Manjaro latest release with KDE, due to the small screen she adjusted the overall scaling to 125%.

But that does obviously not impact the scaling in Evolution, i assume because it’s a GTK application and not KDE

Any ideas how to increase the icon size on the toolbar?
Using a different mail client (e.g. KMail) is not her intention as she’s happy with Evolution in general.

Many thanks in advance