Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
OPERATING ACTIVITIES
Net loss	$ (51,430)	$ (19,839)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	19,256	2,564
Depreciation and amortization	1,722	1,132
Net amortization of premium on available-for-sale securities	819	185
Non-cash interest expense and other adjustments	0	10
Changes in operating assets and liabilities:
Accounts receivable, net	(1,165)	0
Related party receivables	(604)	0
Other receivables	(513)	(330)
Prepaid expenses and other current assets	(2,114)	(128)
Inventory	(2,006)	0
Other assets	(52)	(18)
Accounts payable	302	(60)
Deferred revenue	(139)	250
Deferred rent	870	256
Accrued expenses	919	738
Accrued research and development	231	(133)
Other noncurrent liabilities	(74)	30
Net cash used in operating activities	(33,978)	(15,343)
INVESTING ACTIVITIES
Purchases of property and equipment	(5,588)	(4,407)
Purchase of available-for-sale securities	(169,801)	(75,624)
Proceeds from maturities of available-for-sale securities	92,000	40,250
Investment in equity method investee	0	(50)
Net cash used in investing activities	(83,389)	(39,831)
FINANCING ACTIVITIES
Proceeds from issuance of common stock upon follow-on public offering, net of issuance costs	102,959	0
Proceeds from return of profit	11,403	0
Repurchase of Class A common stock	(35)	(6)
Proceeds from stock option exercises including early exercised options	1,038	578
Proceeds from issuance of Series D-1 preferred stock, net of issuance costs	0	54,896
Payments of deferred offering costs	0	(73)
Net cash provided by financing activities	115,365	55,395
Net increase (decrease) in cash, cash equivalents and restricted cash	(2,002)	221
Cash, cash equivalents and restricted cash, beginning of period	333,928	17,828
Cash, cash equivalents and restricted cash, end of period	331,926	18,049
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash paid for income taxes	605	0
Accounts Payable
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES
Property and equipment purchases	183	20
Deferred offering costs	0	90
Accrued Expenses
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES
Property and equipment purchases	271	0
Deferred offering costs	$ 0	$ 1,006