It being necessary to use shibboleths/code words to authenticate to each other over video chat (eg, to ensure that the person you're speaking to is who they appear to be, not someone else using deepfake puppetry). Really this is an implicit biometric authentication mechanism, and biometrics are usernames, not passwords. (Though I'd love to be wrong about this one.)
Probably worth doing now - eg the ‘Mum I lost my phone, this is my new number’ scam which needs nothing more than SMS.
I've read about this scam and it seems interesting to me - is that a realistic thing that might happen if your relative lost a phone? Perhaps it's a market-specific issue, but I have had multiple phones lost/stolen/broken in my life, but I still have the same number I had since my first phone back in the previous millenium, and I somewhat expect that some kid's phone number will stay the same until they die unless they move overseas and get another phone number there (and probably still keep the old one as well). Don't you have number portability across phones and carriers?