"the injunction would impose irreparable injury"
Irreparable, yes, but not important.
Apple will survive even if Epic wins, and it's not like Apple will have to pay what Epic is not giving now.
Yes, Apple will make less money, but it already has litterally more money than it can spend. It is the top company in the world by market cap and is more valuable than Facebook, Nvidia and TSMC put together. It can take the hit.
Personally, I would not respond to this appeal.