Bug Nested tags of same kind don't act as expected

Let's say I have a text field with the following input:

<uppercase><uppercase>Hello</uppercase> world</uppercase>

I would expect the whole thing to be uppercase, that's how nested tags work in HTML. However, the following result is produced:


I encountered this problem while trying to form dynamic string with rich text tags. If a parent string has the uppercase tag, I would have to smartly remove the tag from the children where necessary for the system to work.