Short answer - no, it makes no difference.

In general, an await basically means "wait for this Promise to resolve before continuing with the rest of the code". But this means an await before the final statement of a function has no effect whatsoever, because there is nothing that needs to happen after the "wait".

As a simple illustration:

const sleep = (delay) => new Promise(resolve => setTimeout(resolve, delay));

const myFunction = async () => {
  console.log("before");
  await sleep(2000);
  console.log("after");
};

myFunction();

and, as you would no doubt expect, there is a 2 second delay between the "before" and "after".

But if you didn't care about the "after", then you don't need the await at all:

const sleep = (delay) => new Promise(resolve => setTimeout(resolve, delay));

const myFunction = async () => {
  console.log("before");
  sleep(2000);
};

myFunction();

You could use await here, and maybe it's better practice in case you later want to add something after - but there's absolutely no need for it. (In this trivial case of course there's no need to have the sleep call at all - but imagine it's a "real" function with a side-effect, like posting to an API.)

It's the same with your React example:

onClick={async() => await restrictOrders()}>

you are awaiting the last (and in this case, only) statement of an anonymous function. Since there's nothing you do afterwards that needs to wait, there's no harm in not having the await there - so most commonly it's not done, I guess to make the inline function expression less verbose.

What has been observed (by me) on some of the apps is this:

Actions taken by the user (such as button-click) result in updating the state. So, in this case, if we have a state-variable like this:

const [ordersRestricted, setOrdersRestricted] = useState(0);

then, the click-handler is like so:

onClick={() => setOrdersRestricted(prev => (prev + 1))}>

Consequently, the corresponding effect (or side-effect) from the action is handled like so:

useEffect(() => {
  const restrictOrders = async () => {
    try {
      const result = await axios.post(`${config.dev_server}/something`);
      // do something with the result
      // typically, update the state (but take care to not change 
      // dependencies, that may lead to infinite looping)
    } catch(e){}
  };
  restrictOrders();
}, [ordersRestricted]);