I thought that is why you might have required it, but on the other hand for malicious actors it's trivial to get a phone number unrelated to them, while legitim

I thought that is why you might have required it, but on the other hand for malicious actors it's trivial to get a phone number unrelated to them, while legitimate users are giving up their only phone number, possibly exposing it to scammers and robocalls (in case of a breach), or having something linking to their real identity. Anyway, hoping you revisit this one day and that's also when I will try your app again. Wishing you luck!