It would not surprise me if Taylor Swift learns the hard way that nearly half her fans don't like her choice of presidential candidate. And of course, nobody insisted she reveal her politics.
Whatever the merits of her music, which obviously speaks to many, the smart thing to do was to encourage people to study the issues and vote for the person and party with which one shares values. Exhortations to "Go Vote" are entirely laudable and offend no one.
Pick a side and you've offended many of your former fans, who now know something about you both you and they would rather they didn't know. Something that makes you less likable, less relatable. Something that "others" you.
It's too late now, that cat is out of the bag and running like a Haitian was chasing it with cleaver. A year from now it will be interesting to see how endorsing Harris played out for both women.