1. Switch bottom tab from Explore (map pin icon) to You (bookmark icon)

2. Scroll down to the very very bottom, until a row of icons (Timeline, Following, Maps) appear

3. Click the rightmost icon, Maps, and you will find a list of maps you have opened before

4. Find the Torii map and click into it

5. Click "View map legend" at bottom of screen

6. Click "Close" in upper right

Yep that's it, just so "simple and straightforward" as most Google products have evolved to be, what a pleasant user journey! Promo-oriented product design really hurts my eyes