How do you use deprecation annotations?

SwiftUI:

@available(iOS, introduced: 13.0, deprecated: 100000.0, renamed: "navigationTitle(_:)")

Why deprecated: 100000.0? It's deprecated but the compiler doesn't show deprecation warning. It's hard remove all deprecated calls if you don't know already and had to eye ball these calls. It's been this way since SwIFTUI 2, now SwiftUI 3 still that same way. Why cannot make removing deprecation easy?

Solution to see SwiftUI deprecation warnings: Don't see any deprecation warning, due to "deprecated: 100000.0"? What's the rationale for marking it this way?! - #6 by Fritzt