Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
OPERATING ACTIVITIES
Net loss	$ (23,646)	$ (16,429)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	8,062	6,039
Depreciation and amortization	875	482
Net amortization of premium on available-for-sale securities	314	152
Non-cash operating lease expense	551	78
Changes in operating assets and liabilities:
Accounts receivable, net	(298)	0
Related party receivables	157	(2)
Other receivables	(174)	(249)
Prepaid expenses and other current assets	(2,850)	(2,589)
Inventory	300	(990)
Other assets	11	30
Accounts payable	(479)	(234)
Deferred revenue	18	6
Accrued expenses	(2,038)	(990)
Operating lease liabilities	46	(93)
Other noncurrent liabilities	0	(83)
Net cash used in operating activities	(19,151)	(14,872)
INVESTING ACTIVITIES
Purchases of property and equipment	(1,080)	(838)
Purchase of available-for-sale securities	0	(30,279)
Proceeds from maturities of available-for-sale securities	12,000	43,000
Net cash provided by investing activities	10,920	11,883
FINANCING ACTIVITIES
Proceeds from issuance of common stock upon follow-on public offering, net of issuance costs	0	103,595
Proceeds from return of profit	0	11,403
Repurchase of Class A common stock	(21)	(2)
Proceeds from exercise of Class A common stock options including early exercised options	773	171
Net cash provided by financing activities	752	115,167
Net increase (decrease) in cash, cash equivalents and restricted cash	(7,479)	112,178
Cash, cash equivalents and restricted cash, beginning of period	233,337	333,928
Cash, cash equivalents and restricted cash, end of period	225,858	446,106
SUPPLEMENTAL DISCLOSURE OF NON-CASH ACTIVITIES
Lease liability obtained in exchange for right-of-use assets	6,855	7,823
Accounts Payable
SUPPLEMENTAL DISCLOSURE OF NON-CASH ACTIVITIES
Property and equipment purchases included in accounts payable and in accrued expenses	204	9
Offering costs in accounts payable and in accrued expenses	0	158
Accrued Liabilities
SUPPLEMENTAL DISCLOSURE OF NON-CASH ACTIVITIES
Property and equipment purchases included in accounts payable and in accrued expenses	183	49
Offering costs in accounts payable and in accrued expenses	$ 0	$ 478