Tools.
Swift debugger fails to print the value of a variable a lot of the time, and even when it succeeds it might print a different value than the one in a real program
Installing swift on linux is an awful experience The current state of Swift for Server and Linux - #18 by cukr
sourcekit-lsp is incomplete, lacking stuff like formatting and global rename
I dislike Xcode in general, for example spm integration is done poorly.