Net Loss Per Share Attributable To Common Stockholders - Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2021	Jul. 31, 2020	Jul. 31, 2021	Jul. 31, 2020
Schedule of Earnings Per Share, Basic and Diluted [Line Items]
Net loss	$ (68,163)	$ (22,938)	$ (130,797)	$ (49,576)
Numerator:
Net loss	$ (68,163)	$ (22,938)	$ (130,797)	$ (49,576)
Denominator:
Net loss per share attributable to Class A and Class B common stockholders, basic (in USD per share)	$ (0.57)	$ (0.67)	$ (1.59)	$ (1.45)
Net loss per share attributable to Class A and Class B common stockholders, diluted (in USD per share)	$ (0.57)	$ (0.67)	$ (1.59)	$ (1.45)
Class A and Class B Common Stock
Schedule of Earnings Per Share, Basic and Diluted [Line Items]
Net loss	$ (68,163)	$ (22,938)	$ (130,797)	$ (49,576)
Numerator:
Net loss	$ (68,163)	$ (22,938)	$ (130,797)	$ (49,576)
Denominator:
Weighted-average shares used in computing net loss per share attributable to Class A and Class B common stockholders, basic (in shares)	120,520,061	34,480,356	82,394,440	34,229,843
Weighted-average shares used in computing net loss per share attributable to Class A and Class B common stockholders, diluted (in shares)	120,520,061	34,480,356	82,394,440	34,229,843
Net loss per share attributable to Class A and Class B common stockholders, basic (in USD per share)	$ (0.57)	$ (0.67)	$ (1.59)	$ (1.45)
Net loss per share attributable to Class A and Class B common stockholders, diluted (in USD per share)	$ (0.57)	$ (0.67)	$ (1.59)	$ (1.45)