CONDENSED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Convertible Preferred Stock
Beginning Balance at Dec. 31, 2019	$ (25,482)	$ 1	$ 1,179	$ (2)	$ (26,660)
Temporary Equity, Beginning Balance, Shares at Dec. 31, 2019						27,283,973
Temporary Equity, Beginning Balance at Dec. 31, 2019						$ 59,815
Beginning Balance, Shares at Dec. 31, 2019		1,600,601
Vesting of shares of common stock subject to repurchase	14		14
Vesting of shares of common stock subject to repurchase, Shares		17,494
Issuance of common stock upon exercise of stock option, net of repurchase	1		1
Issuance of common stock upon exercise of stock option, net of repurchase, Shares		2,871
Share-based compensation expense	482		482
Unrealized gain (loss) on short-term investments	(1)			(1)
Net loss	(8,706)				(8,706)
Ending Balance at Mar. 31, 2020	(33,692)	$ 1	1,676	(3)	(35,366)
Temporary Equity, Ending Balance, Shares at Mar. 31, 2020						27,283,973
Temporary Equity, Ending Balance at Mar. 31, 2020						$ 59,815
Ending Balance, Shares at Mar. 31, 2020		1,620,966
Beginning Balance at Dec. 31, 2019	(25,482)	$ 1	1,179	(2)	(26,660)
Temporary Equity, Beginning Balance, Shares at Dec. 31, 2019						27,283,973
Temporary Equity, Beginning Balance at Dec. 31, 2019						$ 59,815
Beginning Balance, Shares at Dec. 31, 2019		1,600,601
Net loss	(73,464)
Ending Balance at Sep. 30, 2020	334,981	$ 3	435,098	4	(100,124)
Ending Balance, Shares at Sep. 30, 2020		32,568,332
Beginning Balance at Mar. 31, 2020	(33,692)	$ 1	1,676	(3)	(35,366)
Temporary Equity, Beginning Balance, Shares at Mar. 31, 2020						27,283,973
Temporary Equity, Beginning Balance at Mar. 31, 2020						$ 59,815
Beginning Balance, Shares at Mar. 31, 2020		1,620,966
Vesting of shares of common stock subject to repurchase	12		12
Vesting of shares of common stock subject to repurchase, Shares		19,110
Issuance of common stock upon exercise of stock option, net of repurchase	285		285
Issuance of common stock upon exercise of stock option, net of repurchase, Shares		110,425
Share-based compensation expense	566		566
Unrealized gain (loss) on short-term investments	4			4
Net loss	(51,065)				(51,065)
Ending Balance at Jun. 30, 2020	(83,890)	$ 1	2,539	1	(86,431)
Temporary Equity, Ending Balance, Shares at Jun. 30, 2020						27,283,973
Temporary Equity, Ending Balance at Jun. 30, 2020						$ 59,815
Ending Balance, Shares at Jun. 30, 2020		1,750,501
Temporary equity, Issuance of Series B convertible preferred stock, net of issuance costs						$ 64,321
Temporary equity, Issuance of Series B convertible preferred stock, net of issuance costs, Shares						27,066,206
Temporary equity, series B preferred stock purchase right (liability) upon issuance of Series B convertible preferred stock						$ 41,641
Temporary equity, conversion of convertible preferred stock to common stock						$ (165,777)
Temporary equity, conversion of convertible preferred stock to common stock, Shares						(54,350,179)
Conversion of convertible preferred stock to common stock	165,777	$ 1	165,776
Conversion of convertible preferred stock to common stock, Shares		14,689,215
Issuance of common stock upon initial public offering, net of issuance costs	265,130	$ 1	265,129
Issuance of common stock upon initial public offering, net of issuance costs, Shares		16,100,000
Vesting of shares of common stock subject to repurchase	9		9
Vesting of shares of common stock subject to repurchase, Shares		18,246
Issuance of common stock upon exercise of stock option, net of repurchase	36		36
Issuance of common stock upon exercise of stock option, net of repurchase, Shares		10,370
Share-based compensation expense	1,609		1,609
Unrealized gain (loss) on short-term investments	3			3
Net loss	(13,693)				(13,693)
Ending Balance at Sep. 30, 2020	334,981	$ 3	435,098	4	(100,124)
Ending Balance, Shares at Sep. 30, 2020		32,568,332
Beginning Balance at Dec. 31, 2020	321,220	$ 3	439,235	3	(118,021)
Beginning Balance, Shares at Dec. 31, 2020		32,627,963
Vesting of shares of common stock subject to repurchase	9		9
Vesting of shares of common stock subject to repurchase, Shares		15,802
Issuance of common stock upon exercise of stock option, net of repurchase	756		756
Issuance of common stock upon exercise of stock option, net of repurchase, Shares		154,489
Share-based compensation expense	3,347		3,347
Unrealized gain (loss) on short-term investments	31			31
Net loss	(19,373)				(19,373)
Ending Balance at Mar. 31, 2021	305,990	$ 3	443,347	34	(137,394)
Ending Balance, Shares at Mar. 31, 2021		32,798,254
Beginning Balance at Dec. 31, 2020	$ 321,220	$ 3	439,235	3	(118,021)
Beginning Balance, Shares at Dec. 31, 2020		32,627,963
Issuance of common stock upon exercise of stock option, net of repurchase, Shares	257,579
Net loss	$ (63,261)
Ending Balance at Sep. 30, 2021	270,011	$ 3	451,320	(30)	(181,282)
Ending Balance, Shares at Sep. 30, 2021		32,931,580
Beginning Balance at Mar. 31, 2021	305,990	$ 3	443,347	34	(137,394)
Beginning Balance, Shares at Mar. 31, 2021		32,798,254
Vesting of shares of common stock subject to repurchase	9		9
Vesting of shares of common stock subject to repurchase, Shares		15,575
Issuance of common stock upon exercise of stock option, net of repurchase	256		256
Issuance of common stock upon exercise of stock option, net of repurchase, Shares		39,032
Share-based compensation expense	3,690		3,690
Unrealized gain (loss) on short-term investments	(28)			(28)
Net loss	(21,535)				(21,535)
Ending Balance at Jun. 30, 2021	288,382	$ 3	447,302	6	(158,929)
Ending Balance, Shares at Jun. 30, 2021		32,852,861
Vesting of shares of common stock subject to repurchase	8		8
Vesting of shares of common stock subject to repurchase, Shares		15,494
Issuance of common stock upon exercise of stock option, net of repurchase	318		318
Issuance of common stock upon exercise of stock option, net of repurchase, Shares		63,225
Share-based compensation expense	3,692		3,692
Unrealized gain (loss) on short-term investments	(36)			(36)
Net loss	(22,353)				(22,353)
Ending Balance at Sep. 30, 2021	$ 270,011	$ 3	$ 451,320	$ (30)	$ (181,282)
Ending Balance, Shares at Sep. 30, 2021		32,931,580