Briefly: Google Maps Embed API may show directions zoomed in too far.
The origin and destination are visible inside the iframe.
Why is it bad? It's zoomed in too far. The origin and destination are outside the edges of the iframe.
If you click the [-] zoom-out button, then you can see the origin and destination.
UPDATE: Did this get fixed? This is how this map used to look:
Why is it ugly?
The zoom=14 parameter is specified explicitly.
This just happens to work for these specific directions,
but in general it is not at all obvious
what is "right" value for the zoom= parameter.
"Right" means the largest zoom value
(zoomed in as much as possible)
so the origin and destination are inside the iframe.