Firefox when asked to block format (formatting over a block with blockquote, h1, ...) has a special case for blockquote (it is documented in https://developer.mozilla.org/docs/Web/API/Document/execCommand at formatBlock command) and will wrap any element instead of replacing existing block formatting. Thus the code not expecting it was not able to remove a blockquote in firefox once introduced. opw-1903735 closes #28587