Because the regular block year 2022-2025 has sub-blocks 2022-23 and 2024-25. The employee's 8th LTC (All India) fell in 2024 (first year of sub-block 2024-25). The second year of that sub-block (2025) therefore has no separate LTC entitlement — it was used up by the 8th occasion.
Source: LTC FAQ 16