it seems the Mac App Store is having a weird bug since around 3 days. while it claims to have update apps like normal, they aren't actually updated. inspecting the apps in the Finder reveals that the version number is still the old one. but deleting the app and re-downloading from the Mac App Store yields the new version. seen myself with 'Vimeo' but customers also report the very same problem e.g. with 'OneDrive' and 'WhatsApp'
i'd file a bug report but they won't look at it in 2019 so there seems little point.