Net Loss per Share - Schedule of Potentially Dilutive Securities Excluded from Computation of Net Loss per Share (Details) - shares	12 Months Ended
	Jan. 31, 2022	Jan. 31, 2021	Jan. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share (in shares)	52,196,715	75,126,464	254,581,401
Redeemable convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share (in shares)	0	0	169,921,272
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share (in shares)	42,043,097	64,574,656	80,903,200
Common stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share (in shares)	0	0	32,336
Unvested restricted stock awards and early exercised stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share (in shares)	426,094	987,544	3,724,593
RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share (in shares)	9,612,323	9,348,557	0
Employee stock purchase rights under the 2020 ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share (in shares)	115,201	215,707	0