Stock-Based Compensation - Summary of Stock Option Activities (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Number of options outstanding, beginning of period	435,342
Number of options granted	2,386,990
Number of options, cancelled and forfeited	(25,551)
Number of options exercised	(59,466)
Number of options outstanding, ending of period	2,737,315	435,342
Number of options, vested and expected to vest	2,737,315
Number of options exercisable, end of period	206,339
Weighted average exercise price outstanding, beginning of period	$ 0.52
Weighted average exercise price, options granted	3.11
Weighted average exercise price, options cancelled and forfeited	1.86
Weighted average exercise price, options exercised	1.86
Weighted average exercise price outstanding, end of period	2.74	$ 0.52
Weighted average exercise price, options vested and expected to vest	2.74
Weighted average exercise price, options exercisable	$ 0.31
Weighted average remaining contracted terms (in years) outstanding, beginning of period		9 years 2 months 8 days
Weighted average remaining contracted terms (in years) outstanding, end of period	9 years 3 months 29 days
Weighted average remaining contracted terms (in years), vested and expected to vest	9 years 3 months 29 days
Weighted average remaining contracted terms (in years), exercisable at end of period	8 years 4 months 20 days
Aggregate intrinsic value outstanding, beginning of period	$ 415
Aggregate intrinsic value options exercised	150
Aggregate intrinsic value outstanding, end of period	41,727	$ 415
Aggregate intrinsic value options vested and expected to vest	41,727
Aggregate intrinsic value options exercisable	$ 3,646