As other commenters have mentioned - if your project violates React patents, and you switch to Preact, it almost certainly continues to violate those same patents.

Vue is also based on React, it uses the same exact principles internally, although in a less concise and more complex way as it leans heavily in Angulars direction on the outside. All templates are either transpiled or evaluated into createElement-like functions, from then on it has a v-dom and works/diffs/renders/composes like React.

This could "violate a react patent" according to you:

  const Test = () => createElement("div", null, "hello word")

No one has ever seen nor referenced a patent for this, but if we're really at that point then i'm afraid everything would violate such a patent.