Blue hydrogen comparisons: what leakage rate is fair?

Pre-combustion capture reads tidy on a flow sheet because the CO2 stream is concentrated. The hard part, at least in public arguments, is the upstream gas boundary.

The papers I would put next to each other are Antonini et al. on gas and biomethane routes (doi:10.1039/d0se00222d), Howarth and Jacobson's critique (doi:10.1002/ese3.956), and Bauer et al. on climate impacts (doi:10.1039/d1se01508g).

If you were reviewing a blue hydrogen claim, what methane leakage assumption would make you stop reading, and what data would make you trust it?