This matches existing patterns in chronik-client. IMO we should stick to hex strings for API returns. API returns for tokens -- esp GenesisInfo -- needs to be cached as it never changes. Caching Uint8Array is complicated because it is not JSON. But hex strings are easy.
ecash-lib has available toHex and fromHex methods that make conversion easy depending on dev needs.
auth as a Uint8Array would require special handling in Cashtab's existing caching mechanism if we do not make this change.