STOCK-BASED COMPENSATION PLAN - Schedule of Share-based Payment Arrangement, Option and RSU Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2022	Dec. 31, 2021
Options Outstanding
Options outstanding at beginning of period (in shares)	3,796,530
Options granted (in shares)	65,717
Options released (in shares)	(138,617)
Options forfeited (in shares)	(16,517)
Options outstanding at end of period (in shares)	3,707,113	3,796,530
Options vested and exercisable (in shares)	1,626,013	1,827,374
Weighted average exercise price
Weighted average exercise price of options outstanding at beginning of period (in USD per share)	$ 0.83
Weighted average exercise price of options granted (in USD per share)	8.00
Weighted average exercise price of options released (in USD per share)	0.30
Weighted average exercise price of options forfeited (in USD per share)	0.36
Weighted average exercise price of options outstanding at end of period (in USD per share)	0.98	$ 0.83
Weighted average exercise price of options vested and exercisable (in USD per share)	$ 0.56	$ 0.31
Options, Additional Disclosures
Weighted average remaining contractual term of options outstanding	8 years 10 days	8 years 29 days
Weighted average remaining contractual term of options vested and exercisable	7 years 4 months 28 days	7 years 2 months 12 days
Aggregate intrinsic value of options outstanding	$ 17,012	$ 40,274
Aggregate intrinsic value of options vested and exercisable	$ 8,140	$ 20,337
RSUs
RSUs
Units outstanding at beginning of period (in shares)	3,392,153
Units granted (in shares)	2,150,859
Units released (in shares)	(873,070)
Units forfeited (in shares)	(35,974)
Units outstanding at end of period (in shares)	4,633,968	3,392,153
Weighted average grant date fair value per Share
Weighted average grant date fair value per share of units outstanding at beginning of period (in USD per share)	$ 10.69
Weighted average grant date fair value per share of units granted (in USD per share)	5.46
Weighted average grant date fair value per share of units released (in USD per share)	11.12
Weighted average grant date fair value per share of units forfeited (in USD per share)	10.15
Weighted average grant date fair value per share of units outstanding at end of period (in USD per share)	$ 8.82	$ 10.69

Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).