US Web3 offer background checks — what tends to go wrong at the last step? (DeFi / Solidity)

I’m in late-stage interviews for a DeFi-focused Solidity developer role with a US-based team (remote). They said the offer depends on a standard background check + employment verification, and I’m a bit nervous about late-stage surprises.

My history isn’t super “corporate neat” — mix of payroll roles and contract/protocol work (GitHub + invoices + founder/EM references, not always an HR email).

For people who’ve been through this with US Web3 teams: what usually becomes a dealbreaker at the last step? And what should I prep upfront so the check doesn’t delay or derail the offer?