Balance sheet components - Summary of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Sep. 30, 2022
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 186,437	$ 171,218
Less: Accumulated depreciation and amortization	(45,659)	(31,777)
Property and equipment, net	140,778	139,441
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	104,677	62,285
Furniture, fixtures and other equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	3,493	2,332
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	3,072	2,814
Computer software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	2,854	1,693
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	56,810	14,371
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 15,531	$ 87,723