This could be either be a Hugo or Goldmark issue. When a link is placed between brackets, it leaves a space at the opening of the bracket. For example, copy the sentence below to a markdown file then build the site and observe.
Turns out it was my markdown render hook adding the trailing white spaces due to a missing - at the end of the last variable. I need to audit my site now because I had a similar issue yesterday with the dashes used to trim white space.