When I pair a new device in Signal, or change my phone number, I cannot see my any previous messages. However, in WhatsApp I can. As I understand it, that's a

When I pair a new device in Signal, or change my phone number, I cannot see my any previous messages. However, in WhatsApp I can. As I understand it, that's a security weak spot with WhatsApp, that could (in theory) allow Meta read users messages. Is it the case?