To estimate S&P's adjusted leverage trend for ENI S.P.A. for 2022, we analyze the changes in the Net Debt to EBITDA ratio between 2021 and 2022.

1. **EBITDA Calculation**:
   - **2021**: Operating Profit (Profit Loss From Operating Activities) was €12.34 billion and Depreciation & Amortisation was €7.06 billion. Adding these yields a base EBITDA of approximately €19.40 billion.
   - **2022**: Operating Profit increased to €17.51 billion and D&A was €7.21 billion. This gives a base EBITDA of roughly €24.72 billion. 
   *(Note: Adjustments for impairments or write-offs further increase EBITDA in both years, maintaining the strong upward trend).*

2. **Net Debt Calculation**:
   - **2021**: Total Borrowings (Short-term + Current Portion of Long-term + Long-term Borrowings) stood at €27.79 billion. Including lease liabilities (€5.34 billion) gives a gross debt of €33.13 billion. Subtracting Cash and Cash Equivalents (€8.25 billion) results in a Net Debt of around €24.88 billion.
   - **2022**: Total Borrowings were €26.92 billion. Including lease liabilities (€4.95 billion) gives a gross debt of €31.87 billion. Subtracting the elevated Cash and Cash Equivalents (€10.16 billion) yields a Net Debt of roughly €21.71 billion.

3. **Net Debt / EBITDA Ratio**:
   - For **2021**: €24.88B / €19.40B ≈ **1.28x**
   - For **2022**: €21.71B / €24.72B ≈ **0.88x**

The gap in the Net Debt to EBITDA ratio year-on-year is approximately -0.40x. Because the ratio dropped by more than 0.3x (meaning the gap is lower than -0.3x), the leverage trend falls into the "Improving" category. 

<answer>Improving</answer>