Line break moves when editing much lower line

This is very minor but

Sometimes when I type on a line, the line breaks in previous paragraphs move around. It seems Obsidian/CSS/interface (what’s actually doing this?) is recalculating the justification as I type, even though the paragraph is distinct. (This behavior makes sense when you’re editing the lines of the same paragraph, as the CSS/etc tries to resolve paragraph rules.)

I can’t reproduce this problem – it seems to happen randomly, though fairly often – and it doesn’t occur in the default CSS, so I don’t consider this a bug.

Any idea what could be causing this? I’m not very bothered by it but very curious.

In case that description is as unclear to you as it is to me on a second read, here’s an example:

Say I have the following (I have manually inserted line breaks to imitate the problem – so this may not look right on all devices)

Phasellus laoreet lorem vel dolor
tempus vehicula. Paullum deliquit,
ponderibus modulisque suis ratio
utitur.

Quisque ut dolor gravida, placerat
libero vel, euismod.

But when I type the next word in the second paragraph, notice how the justification changes on the first paragraph:

Phasellus laoreet lorem vel dolor
tempus vehicula. Paullum deliquit,
ponderibus modulisque suis ratio utitur.

Quisque ut dolor gravida, placerat
libero vel, euismod. Mag