Fair Value Measurements (Q1) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Schedule of Fair Value Liabilities Measured on Recurring Basis

The following table presents information about the Company’s liabilities that are measured at fair value on a recurring basis at March 31, 2024 and December 31, 2023, and indicates the fair value hierarchy of the valuation inputs the Company utilized to determine such fair value (in thousands):

	Level	March 31, 2024	December 31, 2023
Liabilities:
Warrant liability – Public Warrants	1	$875	$375
Warrant liability – Private Placement Warrants	3	560	210
Total warrant liability		$1,435	$585

The following table presents information about the Company’s liabilities that are measured at fair value on a recurring basis at December 31, 2023 and 2022, and indicates the fair value hierarchy of the valuation inputs the Company utilized to determine such fair value (in thousands):

	Level	December 31, 2023	December 31, 2022
Liabilities:
Warrant liability – Public Warrants	1	$375	$1,250
Warrant liability – Private Placement Warrants	3	210	840
Total warrant liability		$585	$2,090

Schedule of Derivative Liabilities at Fair Value

The following tables summarizes the changes in the fair value of the warrant liabilities (in thousands):

	Three Months Ended March 31, 2024
	Public Warrants	Private Placement Warrants	Warrant Liabilities
Fair value, beginning of period	$375	$210	$585
Change in valuation inputs or other assumptions	500	350	850
Fair value, end of period	$875	$560	$1,435

	Three Months Ended March 31, 2023
	Public Warrants	Private Placement Warrants	Warrant Liabilities
Fair value, beginning of period	$1,250	$840	$2,090
Change in valuation inputs or other assumptions	(375)	(350)	(725)
Fair value, end of period	$875	$490	$1,365

The following tables summarize the changes in the fair value of the warrant liabilities (in thousands):

	Year Ended December 31, 2023
	Public Warrants	Private Placement Warrants	Warrant Liabilities
Fair value, beginning of period	$1,250	$840	$2,090
Change in valuation inputs or other assumptions	(875)	(630)	(1,505)
Fair value, end of period	$375	$210	$585

	Year Ended December 31, 2022
	Public Warrants	Private Placement Warrants	Warrant Liabilities
Fair value, beginning of period	$16,750	$10,710	$27,460
Change in valuation inputs or other assumptions	(15,500)	(9,870)	(25,370)
Fair value, end of period	$1,250	$840	$2,090

Schedule of Fair Value Measurement Inputs and Valuation Techniques

The following table provides quantitative information regarding Level 3 fair value measurements inputs at their measurement dates:

	March 31, 2024	December 31, 2023
Exercise price	$11.50	$11.50
Stock price	$1.33	$0.72
Volatility	83.0%	87.5%
Term (years)	2.21	2.46
Risk-free interest rate	4.55%	4.13%

The following table provides quantitative information regarding Level 3 fair value measurements inputs at their measurement dates:

	December 31, 2023	December 31, 2022
Exercise price	$11.50	$11.50
Stock price	$0.72	$1.01
Volatility	87.5%	82.3%
Term (years)	2.46	3.46
Risk-free interest rate	4.13%	4.17%