CONDENSED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (Unaudited) - USD ($) $ in Thousands	Total		Redeemable Convertible Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Deficit
Beginning balance at Dec. 31, 2019	$ (25,665)			$ 2	$ 699	$ (26,366)
Beginning balance, shares at Dec. 31, 2019			6,712,085
Beginning balance at Dec. 31, 2019			$ 30,960
Beginning balance, Shares at Dec. 31, 2019				2,257,740
Issuance of common stock upon exercise of stock options	198			$ 1	197
Issuance of common stock upon exercise of stock options, shares				255,334
Issuance of Series B redeemable convertible preferred stock, net of issuance costs			$ 17,466
Issuance of Series B redeemable convertible preferred stock, net of issuance costs, shares			3,754,084
Issuance of Series C redeemable convertible preferred stock			$ 58,677
Issuance of Series C redeemable convertible preferred stock, shares			10,919,468
Issuance of Series C redeemable convertible preferred stock upon conversion of notes payable and accrued interest			$ 13,978
Issuance of Series C redeemable convertible preferred stock upon conversion of notes payable and accrued interest, shares			2,593,110
Stock-based compensation	235				235
Net loss	(20,161)					(20,161)
Ending balance at Sep. 30, 2020	(45,393)			$ 3	1,131	(46,527)
Ending balance, Shares at Sep. 30, 2020			23,978,747
Ending balance at Sep. 30, 2020			$ 121,081
Ending balance, Shares at Sep. 30, 2020				2,513,074
Beginning balance at Jun. 30, 2020	(33,746)			$ 2	969	(34,717)
Beginning balance, shares at Jun. 30, 2020			10,466,169
Beginning balance at Jun. 30, 2020			$ 48,426
Beginning balance, Shares at Jun. 30, 2020				2,444,904
Issuance of common stock upon exercise of stock options	45			$ 1	44
Issuance of common stock upon exercise of stock options, shares				68,170
Issuance of Series C redeemable convertible preferred stock			$ 58,677
Issuance of Series C redeemable convertible preferred stock, shares			10,919,468
Issuance of Series C redeemable convertible preferred stock upon conversion of notes payable and accrued interest			$ 13,978
Issuance of Series C redeemable convertible preferred stock upon conversion of notes payable and accrued interest, shares			2,593,110
Stock-based compensation	118				118
Net loss	(11,810)					(11,810)
Ending balance at Sep. 30, 2020	(45,393)			$ 3	1,131	(46,527)
Ending balance, Shares at Sep. 30, 2020			23,978,747
Ending balance at Sep. 30, 2020			$ 121,081
Ending balance, Shares at Sep. 30, 2020				2,513,074
Beginning balance at Dec. 31, 2020	$ (62,308)	[1]		$ 3	1,403	(63,714)
Beginning balance, shares at Dec. 31, 2020	23,978,747	[1]	23,978,747
Beginning balance at Dec. 31, 2020	$ 121,080	[1]	$ 121,080
Beginning balance, Shares at Dec. 31, 2020				2,712,694
Conversion of redeemable convertible preferred shares into common stock	121,080			$ 24	121,056
Conversion of redeemable convertible preferred shares into common stock, shares			(23,978,747)
Conversion of redeemable convertible preferred shares into common stock			$ (121,080)
Conversion of redeemable convertible preferred shares into common stock, shares				23,978,747
Conversion of convertible notes into common stock	24,982			$ 2	24,980
Conversion of convertible notes into common stock, shares				1,470,947
Issuance of common stock upon IPO, net of issuance costs	159,898			$ 10	159,888
Issuance of common stock upon IPO, net of issuance costs, shares				10,350,000
Issuance of common stock upon exercise of stock options	$ 516				516
Issuance of common stock upon exercise of stock options, shares	440,055			440,055
Issuance of common stock under Employee Stock Purchase Plan (ESPP)	$ 332				332
Issuance of common stock under Employee Stock Purchase Plan, shares				39,811
Issuance of common stock for settlement of restricted stock units, Shares				11,250
Stock-based compensation	6,500				6,500
Net loss	(57,012)					(57,012)
Ending balance at Sep. 30, 2021	$ 193,988			$ 39	314,675	(120,726)
Ending balance, Shares at Sep. 30, 2021	0
Ending balance, Shares at Sep. 30, 2021				39,003,504
Beginning balance at Jun. 30, 2021	$ 215,800			$ 39	308,991	(93,230)
Beginning balance, Shares at Jun. 30, 2021				38,684,546
Issuance of common stock upon exercise of stock options	324				324
Issuance of common stock upon exercise of stock options, shares				267,897
Issuance of common stock under Employee Stock Purchase Plan (ESPP)	332				332
Issuance of common stock under Employee Stock Purchase Plan, shares				39,811
Issuance of common stock for settlement of restricted stock units, Shares				11,250
Stock-based compensation	5,028				5,028
Net loss	(27,496)					(27,496)
Ending balance at Sep. 30, 2021	$ 193,988			$ 39	$ 314,675	$ (120,726)
Ending balance, Shares at Sep. 30, 2021	0
Ending balance, Shares at Sep. 30, 2021				39,003,504

[1] The balance sheet as of December 31, 2020 is derived from the audited financial statements as of that date