Embedded google map stopped working

I pasted this link: https://www.google.com/maps/d/embed?mid=za0Bx0koO4sk.kHCbG4TApEP4
On a single line on my two Discourse forums.

It works on one of my forum, and here’s the cooked code:

<div class="maps-onebox">
<iframe src="https://www.google.com/maps/d/embed?mid=13xLbRXoFU-UIUoTiOwJdvLzkoUw" width="690" height="400" frameborder="0" style="border:0" seamless="seamless" sandbox="allow-same-origin allow-scripts allow-forms allow-popups allow-popups-to-escape-sandbox allow-presentation"></iframe>
</div>

On the forum on which it doesn’t work, here’s the cooked:

<div class="maps-onebox">
<iframe width="690" height="400" frameborder="0" style="border:0" data-unsanitized-src="https://www.google.com/maps/d/embed?mid=za0Bx0koO4sk.kHCbG4TApEP4" seamless="seamless" sandbox="allow-same-origin allow-scripts allow-forms allow-popups allow-popups-to-escape-sandbox allow-presentation"></iframe>
</div>

Note that there is a data-unsanitized-src attribute in the iframe on the forum where it doesn’t work.

Both forum are using 2.6.0.beta3 ( b8015ab654 )

And I can repro on try.discourse.org:

Note that the generated iframe also has a data-unsanitized-src attribute.