Net loss per share - Basic and diluted net loss per share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Numerator:
Net loss	$ (112,717)	$ (66,819)	$ (51,010)
Denominator:
Weighted average ordinary shares outstanding, basic	29,660,659	25,061,734	19,145,938
Weighted average ordinary shares outstanding, diluted	29,660,659	25,061,734	19,145,938
Net loss per share, basic	$ (3.80)	$ (2.67)	$ (2.66)
Net loss per share, diluted	$ (3.80)	$ (2.67)	$ (2.66)