The ops manager who starts making decisions unilaterally is not being insubordinate.

They are filling a vacuum.

Someone has to decide.

The founder is unavailable, underwater, or simply no longer interested in that category of problem.

The ops manager has seen the same issue go unresolved for six months.

So they decide.

The founder notices.

Calls it a culture problem.

Maybe calls it a communication problem.

It is neither.

It is an organization that has never defined who owns what.

The ops manager did not take authority.

The company left it on the floor, and someone picked it up.

The question is not how to stop it.

The question is why it took this long for someone to act.