Stockholders' Deficit - Schedule of Stock Option Activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021 USD ($) $ / shares shares	Dec. 31, 2020 $ / shares shares
Equity [Abstract]
Number of Shares Available for Grant, Outstanding Beginning balance	67,010
Number of Shares Available for Grant, Options authorized	1,653,955
Number of Shares Available for Grant, Options granted	(1,784,086)
Number of Shares Available for Grant, Options forfeited or cancelled	(122,308)
Number of Shares Available for Grant, Outstanding Ending balance	59,187	67,010
Number of Shares Underlying Outstanding Options, Beginning balance	2,466,594
Number of Shares Underlying Outstanding Options, Granted	1,784,086
Number of Shares Underlying Outstanding Options, Exercised	(1,957,478)
Number of Shares Underlying Outstanding Options, Forfeited or Cancelled	122,308
Number of Shares Underlying Outstanding Options, Ending balance	2,170,894	2,466,594
Number of Shares Underlying Outstanding Options, Shares Exercisable	1,451,709
Number of Shares Underlying Outstanding Options, Vested and Expected to Vest	2,170,894
Weighted Average Exercise Price, Outstanding beginning balance | $ / shares	$ 0.61
Weighted Average Exercise Price, Options granted | $ / shares	11.25
Weighted Average Exercise Price, Options exercised | $ / shares	0.61
Weighted Average Exercise Price, Options forfeited or cancelled | $ / shares	1.48
Weighted Average Exercise Price, Oustanding ending balance | $ / shares	9.31	$ 0.61
Weighted Average Exercise Price, Shares exercisable | $ / shares	9.28
Weighted Average Exercise Price, vested and expected to vest | $ / shares	$ 9.31
Weighted Average Remaining Contractual Term (in years), Outstanding	8 years 10 months 9 days	5 years 2 months 15 days
Weighted Average Remaining Contractual Term (in years), Shares exercisable	8 years 6 months 25 days
Weighted Average Remaining Contractual Term (in years), Vested and Expected to Vest	8 years 10 months 9 days
Aggregate Intrinsic Value, Outstanding | $	$ 8,283
Aggregate Intrinsic Value, Shares exercisable | $	5,579
Aggregate Intrinsic Value, Vested and expected to vest | $	$ 8,283