Unaudited Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Convertible Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Temporary equity, Balance at Dec. 31, 2019		$ 122,465
Temporary equity, Balance, shares at Dec. 31, 2019		85,093,688
Balance at Dec. 31, 2019	$ (78,237)			$ 5,164	$ 41	$ (83,442)
Balance, shares at Dec. 31, 2019			2,484,848
Issuance of common stock from initial public offering, net of issuance costs	76,898		$ 1	76,897
Issuance of common stock from initial public offering, net of issuance costs, shares			6,540,000
Conversion of preferred stock to common stock from completion of initial public offering	122,465		$ 2	122,463
Conversion of preferred stock to common stock from completion of initial public offering, shares			16,685,014
Stock Issued During Period Value Conversion Of Convertible Warrant	259			259
Conversion of convertible preferred stock warrant to common stock warrant	3,151			3,151
Exercise of stock options	69			69
Exercise of stock options, shares			54,266
Vesting of early exercised stock options	73			73
Vesting of early exercised stock options, shares			145,360
Unrealized gain (loss) on available-for-sale securities, net	(27)				(27)
Net loss	(26,488)					(26,488)
Balance at Sep. 30, 2020	98,163		$ 3	208,076	14	(109,930)
Balance, shares at Sep. 30, 2020			25,909,488
Temporary equity, Conversion of preferred stock to common stock from completion of initial public offering, shares		(85,093,688)
Temporary equity, Conversion of preferred stock to common stock from completion of initial public offering		$ (122,465)
Temporary equity, Balance at Jun. 30, 2020		$ 122,465
Temporary equity, Balance, shares at Jun. 30, 2020		85,093,688
Balance at Jun. 30, 2020	(94,213)			6,584	79	(100,876)
Balance, shares at Jun. 30, 2020			2,600,373
Issuance of common stock from initial public offering, net of issuance costs	76,898		$ 1	76,897
Issuance of common stock from initial public offering, net of issuance costs, shares			6,540,000
Conversion of preferred stock to common stock from completion of initial public offering	122,465		$ 2	122,463
Conversion of preferred stock to common stock from completion of initial public offering, shares			16,685,014
Stock Issued During Period Value Conversion Of Convertible Warrant	259			259
Conversion of convertible preferred stock warrant to common stock warrant	1,791			1,791
Exercise of stock options	58			58
Exercise of stock options, shares			35,882
Vesting of early exercised stock options	24			24
Vesting of early exercised stock options, shares			48,219
Unrealized gain (loss) on available-for-sale securities, net	(65)				(65)
Net loss	(9,054)					(9,054)
Balance at Sep. 30, 2020	98,163		$ 3	208,076	14	(109,930)
Balance, shares at Sep. 30, 2020			25,909,488
Temporary equity, Conversion of preferred stock to common stock from completion of initial public offering, shares		(85,093,688)
Temporary equity, Conversion of preferred stock to common stock from completion of initial public offering		$ (122,465)
Balance at Dec. 31, 2020	$ 89,279		$ 3	210,021	1	(120,746)
Balance, shares at Dec. 31, 2020	25,969,442		25,969,442
Conversion of convertible preferred stock warrant to common stock warrant	$ 5,260			5,260
Exercise of stock options	$ 1,096			1,096
Exercise of stock options, shares	489,179		489,179
Vesting of early exercised stock options	$ 20			20
Vesting of early exercised stock options, shares			28,262
Issuance of common stock from employee stock purchase plan	147			147
Issuance of common stock from employee stock purchase plan, shares			48,335
Unrealized gain (loss) on available-for-sale securities, net	1				1
Net loss	(48,681)					(48,681)
Balance at Sep. 30, 2021	$ 47,122		$ 3	216,544	2	(169,427)
Balance, shares at Sep. 30, 2021	26,535,218		26,535,218
Balance at Jun. 30, 2021	$ 63,259		$ 3	214,348	7	(151,099)
Balance, shares at Jun. 30, 2021			26,505,924
Conversion of convertible preferred stock warrant to common stock warrant	2,154			2,154
Exercise of stock options	37			37
Exercise of stock options, shares			22,368
Vesting of early exercised stock options	5			5
Vesting of early exercised stock options, shares			6,926
Unrealized gain (loss) on available-for-sale securities, net	(5)				(5)
Net loss	(18,328)					(18,328)
Balance at Sep. 30, 2021	$ 47,122		$ 3	$ 216,544	$ 2	$ (169,427)
Balance, shares at Sep. 30, 2021	26,535,218		26,535,218