We tried recreating the notification blocks you have here, and so far they’re migrating properly.
This is the block that what we think you have in your content:
<!-- wp:ugb/notification {"color":"#8ed1fc","textColor":"#313131"} -->
<div class="wp-block-ugb-notification ugb-notification ugb-notification--type-success" style="background-color:#8ed1fc;color:#313131"><p style="color:#313131"><strong>Why is everything sponsored?</strong><br>You’ll notice that a lot of things are sponsored in Courmayeur. From Bar Le Dahu being sponsored by Kia to the lifts sponsored by Emporio Armani, the speed trackers sponsored by BMW, and lounges sponsored by Audemars Piguet. Since Courmayeur is a ritzy area, there is always something going on from a brand perspective. </p></div>
<!-- /wp:ugb/notification -->
This migrated properly.
We found the notifications in your site to have a data-carousel-extra
attribute though. Not sure where this attribute comes from, I imagine this is added in dynamically in the frontend. If that’s right then it shouldn’t have a problem.