Consider this wikitext `ABC [[Category:Foo]]DEF. The old parser in core effectively renders this as ABCDEF and Parsoid renders this as ABC DEF. This may just be an accidental side effect of other whitespace behavior around category links, but this difference is a source of visual diff noise on a large number of enwikivoyage pages.
See this on Parsoid vs this with the old parser. See the "By Plane" section and the IATA superscript after the DHM text.
EDIT: Updated task to include interlanguage links as well.