A local variable, parameter, or inherited member shares a name with a state variable. Reads/writes silently hit the wrong one, a classic source of 'the value never changed' bugs and access-control mistakes.
// function init(address owner) public { owner = owner; } // self-assign // the parameter shadows the state var; state `owner` is never set.
// rename to avoid shadowing (e.g. _owner param vs owner state)
function setOwner(address _owner) external { owner = _owner; }
Largest recorded losses in the same failure class — related, not the same bug:
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