how to call a function after completion of setting a state variable of a functional component in reactjs

I have a state variable where it is continuously changing and after the final state change I have to call a function which removes duplicate from final state variable.

while I am setting state variable, I am using prevstate to merge the present state value

code is below

const setevent = async(events) =>{
    await setevent((prevstate) => [...prevstate,...events])
}

I have to call a function using final event variable as props.

how can I do this?

actually I have seen a approach where after completing the setstate it is like below

const setevent = async(event) =>{
    await setevent(event,() => {
      //calling the function which I need
      getunique(event)
  })
}

but I cant make it work because I am already using prevState.

Thanks in advance