Income taxes - Schedule of movement of deferred tax valuation allowance (Details) - CNY (¥) |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Income taxes | |||
| Balance at beginning of the year | ¥ 811,749,130 | ¥ 1,111,583,535 | ¥ 1,064,015,562 |
| Increase | 17,385,339 | 28,617,596 | 82,998,721 |
| Decrease | (5,662,254) | (328,452,001) | (35,430,748) |
| Balance at end of the year | ¥ 823,472,215 | ¥ 811,749,130 | ¥ 1,111,583,535 |