Gmail on the web has a new feature that shows you how much storage you're using with a prominent indicator and a shortcut to Google One.
Clicking your profile picture in the top-right corner reveals a new pill-shaped button at the bottom of the account switcher, displaying your storage usage.
This button also conveniently links you to a page where you can see a breakdown of your storage usage.
The storage indicator is also being rolled out to other Google services, including Google Docs, Sheets, and Slides.