Everything was fine until... something has changed recently where a page break used to just behave like a paragraph mark or formatting symbol. Now it physically fills the rest of the line on which it appears forcing everything else on that line to the left.
Page breaks used to behave like this... (edited image, since I DK how to make Word behave this way any more)

... like my section breaks still do...

Now things look like this...

So it looks like the page break is not just a mark - it's taking up physical space.
For left-aligned text, this is no big deal.
For centred or right-aligned text, it's a problem.
Pre-empting some questions...
"Just place the page break on its own line..."
When I have space at the end of a page, that's fine. However I often have content that takes up a whole page where I don't have room for the page break to sit on its own line...
"So if the page is full, why don't I just let the page break automatically?"
I may have future updates which change the length of that specific chapter, either shortening it or spilling over to the next page. In any case, I want to make sure I force a new page exactly where I want.
The main reason to just make it go back the way it was is that one of my documents is nearly 2000 pages long, with page breaks on most pages.
Thanks.