I noticed over the past couple weeks, when Google announced the before and after search commands that some SEOs didn’t realize that when Google uses brackets, it is there way of quoting a search phrase. Google can’t really use quotes because people can search using with quotes but brackets are safer.
So when Google gives searchers examples or discuss example queries internally at Google – instead of saying a searcher went to Google and searched for “how to tie a shoe” – Google would say a searcher went to Google and searched for [how to tie a shoe].
Here is where Google recently did this as a public example:
Power user note! If you provide only a year, before: & after: translates those into full dates that work, such as follows:
— Google SearchLiaison (@searchliaison) April 9, 2019
Some SEOs were using the  in their search commands.
I explained why on Twitter and John Mueller from Google liked it:
In fact, for the past 10+ years, when I quote queries, I use brackets here.
Forum discussion at Twitter.