Hey @mikolaszko, all my articles were created with the Old Version Edit with View Source option active.
They all are formatted properly now across all my worlds, but when I open them in the New Edit (I can't tell you which is it visual or euclid, as I'm a bit confused which is which, but I can tell you it's the newest one) the formatting breaks.
There was no changes made to bbcode by me.
Just opening the articles in the New Editor breaks formatting without my interference.
The fixing of those broken articles is not an issue at all.
I can handle that.
The only thing I really want is to prevent this from happening in the rest of my articles when I try to edit them in future.