Changing op during `submit` hook does not refresh client

Let's say there are two users, A and B. And there is this on submit middleware hook that converts the content to uppercase:

backend.use("submit", (ctx, cb) => {
  try {
    ctx.op.op[0].si = ctx.op.op[0].si.toUpperCase();
  } catch (e) {}
  cb();
});

When user A writes "q" user B will see "Q" but user A will still see "q" unless he refreshes the browser.

How can I broadcast on submit middleware changes to the client that initiated the op??

Or, otherwise: Is there any other middleware hook meant to do something like this?

Start by reproducing the submit middleware example with two users and trace how the submit hook processes the initiating client's operation. Determine how the transformed content is propagated to that client; done means user A sees the uppercase value without refreshing while user B continues to receive it.