Capitalization and net loss per share - Computation (Details) $ / shares in Units, $ in Thousands	3 Months Ended					9 Months Ended
	Sep. 30, 2024 USD ($) $ / shares shares	Mar. 31, 2024 USD ($)	Sep. 30, 2023 USD ($) $ / shares shares	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Sep. 30, 2024 USD ($) $ / shares shares	Sep. 30, 2023 USD ($) $ / shares shares
Earnings Per Share [Abstract]
Number of ordinary shares per ADS	8					8
Numerator:
Net loss | $	$ (42,962)	$ (25,794)	$ (14,687)	$ (8,807)	$ (16,743)	$ (139,591)	$ (40,237)
Denominator:
Weighted-average shares outstanding, basic (in shares)	651,944,000		638,239,000			648,633,000	631,448,000
Weighted-average shares outstanding, diluted (in shares)	651,944,000		638,239,000			648,633,000	631,448,000
Net loss per share, basic (in dollars per share) | $ / shares	$ (0.07)		$ (0.02)			$ (0.22)	$ (0.06)
Net loss per share, diluted (in dollars per share) | $ / shares	$ (0.07)		$ (0.02)			$ (0.22)	$ (0.06)
Antidilutive securities excluded from computation of loss per share (in shares)	50,200,000		45,900,000			50,200,000	45,900,000