Duplicate id attribute value "oembed-iframe"

On our case, we will remove the id, but it could be a breaking changing.

This seems like something we can write a test case for. I think before attempting a fix here, we'll need a failing test.

@luke.leber We are not sure how to contribute a test for it, as we are removing the attribute id, so we can not test that the id is duplicated, as it does not exist.

Do you refer to creating a test of the current code, testing the ID duplication?

Hey,

The call to Html::getUniqueId should prevent duplicate IDs 🤔.

That's mainly why I'm interested in how this is actually happening. I wasn't able to reproduce this. The only thing I keep coming back to is if perhaps your theme or module is also using that ID without wrapping it in Html::getUniqueId?

If the uniquification is broken, we would have to fix it. Removing that ID would be a backwards compatibility breakage that can't happen until a new major is released.