There are not likely to be any security issues in Allium. It is a simple text editor in SwiftUI and does not do any dynamic memory managment, and filesystem race conditions cannot really be done on iOS or iPadOS.

Nonetheless, just in case, I am opening private vulnerability reporting in case you do happen to find anything. If you somehow do, I'll be seriously impressed! I'll make sure to credit you for your findings. Allium is a completely free project so be aware I will not be able to give any bounties, apologies.