Thank you for your response.
I had asked my question based solely on the visualization, but after extracting the raw data, I found that the values had indeed changed.
When I calculated Theta separately, as you mentioned, it was relatively low at around 0.15.
Since this metric (ARPU) has always had high variance, I thought CUPED might be effective, but it’s unfortunate that it wasn’t.
Is there any other effective variance reduction method available in the growth book that I could try?
Thank you.