Preact is safe according to this. The year limit means Preact can be used reasonably without fear that some hidden, unclaimed patent in the works from Facebook might come out to take it down.
A patent application must be filed within one year from public disclosure or it is barred. Unless Facebook has a…medium.com
I am not comfortable with “paper tiger” comparisons and neither are a significant number of tech companies and organizations like the Apache Foundation. But this one fact, that any patent for React would already have to have been filed by now in order for them to ever come after Preact is enough for me to use Preact (and teach it). Unfortunately a similar equivalent does not exist for GraphQL, which could easily fall under language patents, which are definitely a thing. In fact, the GraphQL adoption scares me even more because it RESTs (pun intended) at the core of tech stacks that use it, not some glorified, strippable UI library.