Thanks for writeup!

“While the expectation is nothing changes in terms of output ... This statement could be misleading

Thanks also for pointing this out. The "nothing changes in terms of output" was in terms of what the end user sees, but I can see how most people reading this post would be thinking in terms of html output, so I will try and get that post updated with something like the following, which also explains the reason for the underlying markup change.

"While the expectation is nothing changes in terms of output for the end user, this is a pretty major change on a technical level for a very popular block, including a change in the underlying markup to align it with the W3C WAI guidelines on grouping of images (https://www.w3.org/WAI/tutorials/images/groups/), so it’d be a huge help to gather as much testing feedback as possible."