SHARE-BASED PAYMENT - Schedule of Stock Options (Details) - $ / shares	9 Months Ended		12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024	Dec. 31, 2023
Number of Shares
Number of shares, outstanding at beginning (in shares)	32,701,399	32,876,682	32,876,682
Number of shares, granted (in shares)	300,000
Number of shares, exercised (in shares)	(33,334)
Number of shares, forfeited (in shares)	(6,514,093)	(1,521,350)
Number of shares, outstanding at ending (in shares)	26,453,972	31,355,332	32,701,399	32,876,682
Number of shares, expected to vest and exercisable (in shares)	26,453,972	31,355,332
Number of shares, exercisable (in shares)	24,320,639	30,088,665
Weighted Average Exercise Price (US$)
Weighted average exercise price, outstanding at beginning (in dollars per share)	$ 5.80	$ 6.01	$ 6.01
Weighted average exercise price, granted (in dollars per share)	3.57
Weighted average exercise price, exercised (in dollars per share)	2.08
Weighted average exercise price, forfeited (in dollars per share)	6.02	4.60
Weighted average exercise price, outstanding at ending (in dollars per share)	5.72	6.08	5.80	$ 6.01
Weighted average exercise price, expected to vest and exercisable (in dollars per share)	5.72	6.08
Weighted average exercise price, exercisable (in dollars per share)	6.11	6.14
Weighted Average Grant Date Fair Value (US$)
Weighted average grant date fair value, outstanding at beginning (in dollars per share)	4.58	4.73	4.73
Weighted average grant date fair value, grant (in dollars per share)	2.99
Weighted average grant date fair value per share, non-vested shares, exercised (in dollars per share)	1.48
Weighted average grant date fair value per share, non-vested shares, forfeited (in dollars per share)	4.52	3.18
Weighted average grant date fair value, outstanding at ending (in dollars per share)	4.58	4.80	$ 4.58	$ 4.73
Weighted average grant date fair value, expected to vest and exercisable (in dollars per share)	4.58	4.80
Weighted average grant date fair value, exercisable (in dollars per share)	$ 4.91	$ 4.89
Weighted Average Remaining Contractual Life
Weighted average remaining contractual, outstanding	4 years 3 months 18 days	5 years	4 years 6 months	5 years 8 months 12 days
Weighted average remaining contractual life, expected to vest and exercisable	4 years 3 months 18 days	5 years
Weighted average remaining contractual life, exercisable	4 years 1 month 6 days	5 years 1 month 6 days