Hi Ekaterina,
from your response to Bob, I finally understood your problem...
this sounds like a bug. However, I can't reproduce this here; not
with HTML and not with FO output. Spacing is exactly the same in
between same-line paras and para with a line break in between.
However, the space between the paras is indeed a bit large but that
should be easy to fix with FO attributes/CSS.
Screenshot from my PDF: https://i.imgur.com/Y1hHwYC.png
(Input paras on the left as a screen, output on the right.)