Fallacy of the single cause
The fallacy of the single cause is when you blame one thing for a big result when lots of things actually played a part. Complex outcomes usually have many causes—circumstances, choices, structures, luck. Picking one cause and ignoring the rest oversimplifies and can be misleading. It's often done to push a narrative or to assign blame, but it doesn't reflect how events actually unfold.
Examples
The recession was caused by the banks.
She got the job because she knew someone.
The team lost because of the referee.
Crime rose because of the new policy.
He's successful because he works hard.