I guess that’s introduced by the pangu lib the theme uses (probably because the OP didn’t set the language of their site correctly). It introduces space(s) between Chinese and western characters to make the text look “nicer”:
IMO, this theme is a bad starting point for someone posting in a Western language. It is geared towards Chinese, and many of its settings must be adjusted for other writing systems. Not to mention that it was last updated three years ago – not what I would consieder “actively developed”.