Ask HN: Am I being unreasonable saying no to Work MFA on personal phone?

I just got 1 day's notice that my SMS-based MFA to get into Work Email (Outlook) is being discontinued. The only option IT is providing is to use Microsoft Authenticator on personal phones.

For reasons that feel wholly irrelevant to the issue, I have decided I don't want to use my personal phone for anything work related. The last time this came up, I was made to feel like a nuisance, and eventually compromised, using my personal phone for SMS-based MFA.

Am I being unreasonable here? Should I just cave and adjust my personal patterns/workflows to make my personal phone available for work use like this?