I have not experienced deliberate self harm when euphoric hypomanic or manic. I have only deliberately hurt myself during mixed states, but never cutting. I rather mostly slapped myself in the face repeatedly and punched walls or hit my head against walls. I don't believe that behavior is likely born from the same place as what you describe. I never self harm any other times other than during my mentioned above.

I have become injured during euphoric manic states (and again mixed states) but they were more like accidents. When manic, I can be reckless, careless, and impulsive in ways, and not be fully aware of risks. What exacerbated them was the fact that when manic, I feel less physical pain than normal. That's pretty major for me because I have a rather high pain tolerance, compared to many, even during stability.

I hope you have discussed this cutting issue at length with your therapist and/or psychiatrist. It is important to identify what it is born from and what purpose such self harm serves for you. In any case, it is unhealthy behavior.