It seems there was a bug cropping up following a previous 1.18 snapshot that was making cats very lazy at scaring away phantoms indeed, as illustrated by this great picture. Yep, those are some complacent little critters letting that phantom just swoop overhead uncontested. Tsk tsk.
Phantoms started being afraid of cats as of a 1.14 update – 18w44a if you want to be fancy about it – and the latest snapshot means that your feline friends can continue to keep them at bay.
That’s all fixed now, though. Additionally, there are various other bug fixes that solve things like crashes occurring after respawning (that’s a big one) among other issues. You can check out the full rundown in Mojang’s blog post with the update notes at that link.
The Minecraft 1.18 release date is November 30. Mojang recently announced the date and news that it’ll bring new world generation and enhanced cave systems, as well as candles – though some features are still “on hold” for now, which you can read about at that link.