My GF has two nibbles on her resume, and both want her to communicate through either Signal or Telegram.
Edit: they requested banking info right off the bat. Said they use it to “confirm you have a checking account” to verify eligibility. Blocked them on Signal, reported to Indeed, for whatever that’s worth.
WhatsApp is a bit different since many countries use that instead of SMS. Suppose it depends on the culture of where you’re applying. Always pays to use caution though.
I live in a WhatsApp dominated country. Never have I ever been contacted by a recruiter or potential employer via WA, much less so from Signal or Telegram. First contact is either a phone call or an email. At some places I’ve worked on, WA has actually been banned and secure communication for work matters is only allowed via the official ICT managed channels. That was a security sensible company though. Other companies allow WA communication except for confidential information that should only move through company servers.