In Galatians 1:6, Paul is amazed the Galatians are so quickly turning to what?

Answer: A different gospel

Paul was amazed they were so quickly deserting the One who called them and turning to a different gospel.

“I am amazed how quickly you are deserting the One who called you by the grace of Christ and are turning to a different gospel— which is not even a gospel. Evidently some people are troubling you and trying to distort the gospel of Christ.”— Galatians 1:6-7 (BSB)