The org-mode documentation states: "With the exception of list items, blank lines belong to the preceding element with the narrowest possible scope. For example, if at the end of a section we have a paragraph and a blank line, that blank line is considered part of the paragraph."
https://orgmode.org/worg/org-syntax.html#org9bc833d So I created a test org-mode document with exactly that scenario described:
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and then I ran a M-x eval-expression (message "%s" (pp-to-string (org-element-parse-buffer))) to see the parse tree. I'll paste the output at the end because its a wall of text, but analyzing it:
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Its only child is a paragraph which has a :begin at 1 and :end at 10, which only includes the line break at the end of "foo bar." but this is exactly the scenario described in the documentation (a paragraph at the end of a section) so I would expect the paragraph to end at 14, not 10.