VisualEditor sometimes breaks a line before a punctuation mark. Punctuation marks such as full stop, comma, semicolon, etc., are supposed to be on the same as the word before them.

See an example from the article "Arquitectura de Barcelona" in the the Catalan Wikipedia:

It's the last thing marked in red: "... Monarquia Hispànica, els...". The comma appears on the second line, but it's supposed to be always in the first.