Income Taxes - Schedule of effective income tax rate reconciliation (Details)	12 Months Ended
	Jan. 01, 2023	Jan. 02, 2022	Jan. 03, 2021
Income Tax Disclosure [Abstract]
Benefit at US (Fiscal 2021) and UK (Fiscal 2020 and Fiscal 2019) UK statutory income tax rate	21.00%	21.00%	19.00%
Permanent differences	(2.00%)	(3.00%)	0.00%
Non deductible expenses	(0.00%)	(3.00%)	0.00%
Change in unrecognized tax benefits	(0.00%)	0.00%	0.00%
Movement in valuation allowances	(9.00%)	(15.00%)	(24.00%)
Change in valuation allowance due to remeasurement of deferred taxes	0.00%	(7.00%)	0.00%
Differences in tax rates in other jurisdictions	(0.00%)	0.00%	1.00%
Change in tax rates	0.00%	7.00%	1.00%
Loss of tax attributes	(13.00%)	0.00%	0.00%
Other	1.00%	0.00%	3.00%
Effective income tax rate	(2.00%)	0.00%	0.00%