This is what gets people subpoena'd and their entirely private messages scrutinised. Happened to a lot of people, including a friend of mine who's affair became a matter of public record after his company was investigated for anti-trust issues. Super unprofessional and legally dangerous.

I keep two phones, one for work, another for private life, and also two laptops for the same reason. The support for multi-identity is very inconvenient on apple[1], and very poor with whatsapp, signal and, really, most apps except for Google's. Shame, really, considering how well funded Apple and Meta are, and how little effort would be needed to implement the 80% of what people need: the ability to chat using different identities, without touching the rest of the OS wiring.

[1] on macos, its possible to create users with multiple apple id associations, but not on iphone