Since mautrix-whatsapp v0.12.0, the bridge deals with more than just phone numbers now,
so it sometimes tries to manage users with Matrix IDs like: `@whatsapp_lid-123456789:example.com`

Ref:

- https://github.com/mautrix/whatsapp/releases/tag/v0.12.0
- https://mau.fi/blog/2025-04-mautrix-release/