There is no option to manage Storage in the browser.
The inbox cannot be sorted by more than one criteria at a time.
The Storage management in the mobile app doesn't allow for multiple file selection and deletion.
When review attachments in the app, it doesn't keep to a file type or update as files are deleted. Selecting "spreadsheets" will still give PDFs, for example.
There is no way to contact customer support outside of the premium phone line. Since the FAQs and chat bot are unhelpful, I'm unwilling to pay for what will likely be equally unhelpful service.