Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Revenue	$ 1,785	$ 584	$ 4,211	$ 1,106
Costs and expenses:
Cost of revenue	3,487	1,330	8,715	2,958
Research and development	84,506	60,041	204,774	100,202
Sales and marketing	910	459	2,629	1,139
General and administrative	28,831	15,271	83,537	27,204
Total costs and expenses	117,734	77,101	299,655	131,503
Loss from operations	(115,949)	(76,517)	(295,444)	(130,397)
Change in fair value of related party convertible loan	0	(11,849)	0	(11,849)
Change in fair value of warrants liability	0	(970)	(326,900)	(970)
Gain on loan extinguishment	0	0	4,183	0
Other income (expense), net	459	(116)	982	(81)
Loss before provision for income taxes	(115,490)	(89,452)	(617,179)	(143,297)
Provision for income taxes	0	0	0	0
Net loss	(115,490)	(89,452)	(617,179)	(143,297)
Accretion of redeemable convertible preferred stock	0	11,943	4,135	11,943
Net loss attributable to common stockholders, basic	(115,490)	(101,395)	(621,314)	(155,240)
Net loss attributable to common stockholders, diluted	$ (115,490)	$ (101,395)	$ (621,314)	$ (155,240)
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (0.54)	$ (1.73)	$ (4.08)	$ (2.70)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.54)	$ (1.73)	$ (4.08)	$ (2.70)
Weighted-average shares used in computing net loss per share, basic (in shares)	212,802,379	58,606,231	152,469,098	57,584,574
Weighted-average shares used in computing net loss per share, diluted (in shares)	212,802,379	58,606,231	152,469,098	57,584,574