Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities
Net loss	$ (118,009)	$ (44,355)	$ (24,734)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation	639	373	348
Stock-based compensation expense	17,056	4,310	406
Amortization of premiums and discounts on marketable securities, net	179	9	0
Amortization of discounts and loan issuance costs	0	29	71
Gain on disposal of property and equipment	(16)	0	0
Noncash interest expense	0	110	7,027
Change in fair value of preferred warrant liability	0	75	15
Changes in operating assets and liabilities:
Prepaid and other assets	(2,510)	(2,444)	(949)
Accounts payable and accrued liabilities	6,043	5,749	436
Accrued compensation	5,788	1,838	1,010
Operating lease right-of-use assets and liabilities, net	461	289	(80)
Deferred revenue	(4,444)	(3,100)	18,940
Net cash (used in) provided by operating activities	(94,813)	(37,117)	2,490
Cash flows from investing activities
Purchases of marketable securities	(85,357)	(6,693)	0
Maturities of marketable securities	6,580	0	0
Purchases of property and equipment	(3,740)	(1,092)	(235)
Net cash used in investing activities	(82,517)	(7,785)	(235)
Cash flows from financing activities
Proceeds from issuance of common stock in public offerings, gross	185,939	298,080	0
Payment of issuance costs related to public offerings	(11,262)	(24,026)	0
Proceeds from exercise of stock/unit options, net of repurchases	930	22	65
Proceeds from issuance of common stock under employee stock purchase plan	709	444	0
Payments on long-term debt	0	(4,683)	(2,800)
Distributions to members	0	0	(106)
Proceeds from issuance of Series C convertible preferred stock, net of issuance costs	0	2,200	72,623
Proceeds from issuance of convertible notes, net of issuance costs	0	0	19,451
Net cash provided by financing activities	176,316	272,037	89,233
Net (decrease) increase in cash, cash equivalents and restricted cash	(1,014)	227,135	91,488
Cash, cash equivalents and restricted cash at beginning of period	321,713	94,578	3,090
Cash, cash equivalents and restricted cash at end of period	320,699	321,713	94,578
Supplemental disclosure of cash flow information:
Cash paid for interest	0	571	322
Supplemental schedule of noncash investing and financing activities:
Right-of-use assets obtained in exchange for operating lease liabilities	12,074	936	807
Costs incurred, but not paid, in connection with purchases of property and equipment included in accounts payable and accrued liabilities	220	118	43
Conversion of convertible preferred stock into common stock upon completion of initial public offering	0	136,920	0
Issuance of Series C convertible preferred stock upon conversion of outstanding convertible notes	0	0	29,510
Reclassification of warrant liability to equity due to adjustment from preferred stock warrant to common stock warrant upon completion of initial public offering	$ 0	$ 120	$ 0