(Loss) income per Share - Schedule of Dilutive Securities (Details) - shares	3 Months Ended		9 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Class B-1 common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	41,432,781	0	41,432,781	51,499,195
Shares underlying the conversion option in the 2030 Convertible Senior Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	18,738,880	18,738,880	18,738,880	18,738,880
Outstanding pre-IPO options issued pursuant to the 2020 Unit Option Plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	1,205,058	1,222,197	1,205,058	2,376,486
Outstanding restricted stock units (“RSUs”)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	1,649,622	2,431,460	1,649,622	2,595,352
Outstanding performance share units (“PSUs”)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	964,545	986,767	964,545	986,767
Outstanding non-qualified stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	623,653	472,381	623,653	472,381