JSFiddle - React, Tailwind, and code Playground

JavaScript

function rename(index, item) {
  var dateStr = item.newName.substring(0, 11);
  var year = dateStr.substring(0, 4);
  var rest = item.newName.substring(11);
  var tmpDate = new Date(dateStr);
  var d = new Date(
    Date.UTC(tmpDate.getFullYear(), tmpDate.getMonth(), tmpDate.getDate())
  );
  var dayNum = d.getUTCDay() || 7;
  d.setUTCDate(d.getUTCDate() + 4 - dayNum);
  var yearStart = new Date(Date.UTC(d.getUTCFullYear(), 0, 1));
  var wNo = Math.ceil(((d - yearStart) / 86400000 + 1) / 7);

  return year + '-' + (wNo < 10 ? '0' : '') + wNo + ' ' + rest;
}

const result = rename(0, { newName: '2022-03-26 Der Jazzer.m4a' });
console.log(result)