Currently, "These words" and "Not these words" are treated differently than "One of these words" or "Exactly this text". The reason is that the first two allow whitespaces as seperators, whereas the other two don't. Also, stemming is applied in both cases.
However, it seems confusing that those seemingly similar fields behave so differently.
Change the field behavior as shown in the mock.
 There are no placeholders for "These words" "None of these words" and "One of these words".
 There is the placeholder indicated in the mock for "Exactly this text"
 "These words" "None of these words" and "One of these words" create pills on comma, whitespace and enter
 Enter stays aware of its context, and still submits the search if there is no pill to create
 "Exactly this text" behaves exactly like the main search bar technically