Change Button Title in iOS 15

I am using new button configuration style as introduce in iOS 15. It works great!

But when I try to change the title, it is also change the font.

Ref similar issue: uibutton.setTitle change text without changing font size

I don't want to go back to old style :(

My try:

var config = self?.btnNext.configuration
    config?.title = "New Title"
self?.btnNext.updateConfiguration()

Thank you,