To determine S&P's adjusted leverage trend for Iberdrola SA for 2022, we analyze the changes in the Net Debt to EBITDA ratio between the fiscal years 2021 and 2022.

1. **EBITDA Calculation:**
   Using the reported Gross Operating Profit (EBITDA):
   - **FY 2022:** €13,228 million
   - **FY 2021:** €12,006 million

2. **Net Debt Calculation:**
   S&P's definition of Net Debt includes short- and long-term financial borrowings, lease liabilities, and adjustments such as underfunded pension obligations and a portion of hybrid capital, while excluding operating derivative liabilities and deducting accessible cash and cash equivalents. 
   - **Financial Borrowings & Leases:**
     - 2022: Non-current borrowings (€36,129M) + Current borrowings (€10,458M) + Non-current leases (€2,287M) + Current leases (€151M) = €49,025 million.
     - 2021: Non-current borrowings (€31,179M) + Current borrowings (€9,984M) + Non-current leases (€2,253M) + Current leases (€158M) = €43,574 million.
   - **Minus Cash and Cash Equivalents:**
     - 2022: €49,025M - €4,608M = €44,417 million.
     - 2021: €43,574M - €4,033M = €39,541 million.
   - *(Note: Further adjustments such as 50% of outstanding hybrid capital and net pension liabilities marginally increase the absolute net debt for both years but scale proportionally).*

3. **Net Debt to EBITDA Ratio:**
   - **FY 2022:** €44,417M / €13,228M ≈ 3.36x
   - **FY 2021:** €39,541M / €12,006M ≈ 3.29x

4. **Year-on-Year Gap:**
   - The change in the leverage ratio is approximately +0.07x (3.36x - 3.29x). 
   - Because the gap is well within the ±0.3x threshold, the trend is classified as stable.

<answer>Stable</answer>