(This is erratic, but Vlad asked me to send examples.)
Frequently, when I go to a Google Maps page, it shows up with an empty pane in place of the map. Sometimes I get a transient "Sorry, an error has occurred" dialog at the bottom; sometimes not.
For example, on the page https://tasteofsomerville.org there is a map at the bottom. When I click "View larger map" there, it opens a GMap page that's just black (attached).
This repros if I open the same URL in a Private Window. (Just to rule out it being related to my logged-in Google session.)
But if I open the same URL in Safari, it works fine (also attached).

I expect Google Maps to work as normal. Things used to work consistently correctly, but it feels like, in the past few months, it's been increasingly flaky for me, to the point where I have problems more often than not.
0.99.133-beta (WebKit 621.1.2.111.4)
Sequoia (15)