For me it was increasing meat and fat and cutting carbs. Doing that has all but eliminated my reflux until I change my diet for a moderate amount of time.
I had a similar experience. Full keto diet and it's gone completely (it used to be a huge problem). I'm not saying that carbs were the sole cause. I think it was a combination of the carbs and fat and just being overweight in general. Losing weight and sticking to a relatively healthy diet can work wonders for your body.