PopcornFX v1 is not in full development anymore, the latest stable version being v1.13.4, and last supported UE4 version 4.21
It's unlikely that we release new PopcornFX versions, and you can expect the plugin support to stop - we'll stop upgrading to latest UE4 versions basically.
However, if you are in a special situation where you really need a v1 plugin upgrade, please reach out to support.
We intend to provide a PopcornFX v1 -> v2 effects upgrader, but that's still in the works
Hope this helps