According to Finnair site, authentication by text/SMS will be discontinued. No date given but my experience after approximately 12 attempts was that it appears to be no longer supported.

My difficulty was that in order to change to email or an authenticator app, I. needed to manage settings by signing into my account. To sign into my account I needed an authenticator code, which I couldn't get!

After a lengthy wait on chat an agent was able to reset my profile and after going through a number of security questions my Login is now seamless. Much easier than before