To calculate the leverage trend, we need the Net Debt / EBITDA ratio for both 2022 and 2023 based on the provided data.

**1. Calculate EBITDA for 2022 and 2021:**
- EBITDA 2022 (period 2022-01-01 to 2023-01-01): 4,954,000,000 EUR
- EBITDA 2021 (period 2021-01-01 to 2022-01-01): 3,529,000,000 EUR

*(Note: The provided fact labels for EBITDA use "Beneficio Bruto De Explotacion Ebitda". The 2022 period corresponds to the year ended 2023-01-01, and the 2021 period corresponds to the year ended 2022-01-01.)*

**2. Calculate Net Debt:**
Net Debt = (Noncurrent Financial Liabilities + Current Financial Liabilities) - (Cash and Cash Equivalents + Other Current Financial Assets)

- **For 2022 (as of 2023-01-01):**
    - Noncurrent Financial Liabilities: 13,999,000,000
    - Current Financial Liabilities: 2,302,000,000
    - Cash and Cash Equivalents: 3,985,000,000
    - Other Current Financial Assets: 408,000,000
    - Net Debt = (13,999,000,000 + 2,302,000,000) - (3,985,000,000 + 408,000,000) = 16,301,000,000 - 4,393,000,000 = 11,908,000,000 EUR

- **For 2021 (as of 2022-01-01):**
    - Noncurrent Financial Liabilities: 15,114,000,000
    - Current Financial Liabilities: 1,698,000,000
    - Cash and Cash Equivalents: 3,965,000,000
    - Other Current Financial Assets: 395,000,000
    - Net Debt = (15,114,000,000 + 1,698,000,000) - (3,965,000,000 + 395,000,000) = 16,812,000,000 - 4,360,000,000 = 12,452,000,000 EUR

**3. Calculate Net Debt / EBITDA Ratio:**
- **Ratio for 2022:** Net Debt 2022 / EBITDA 2022 = 11,908,000,000 / 4,954,000,000 = 2.404x
- **Ratio for 2021:** Net Debt 2021 / EBITDA 2021 = 12,452,000,000 / 3,529,000,000 = 3.528x

**4. Determine Trend:**
The year-on-year change is: 2.404x - 3.528x = -1.124x.

Since the gap (-1.124x) is lower than -0.3x, the trend is "Improving."

<answer>Improving</answer>