JSFiddle - React, Tailwind, and code Playground

JavaScript

var text = "<b>Olá</b>, Usuário<br><i>Seja bem vindo</i>!"
var separador = '<br>';

function removeHTML(str, sep) {
    var partes = str.split(sep);
    return partes.map(function (str) {
        var el = document.createElement('div');
        el.innerHTML = str;
        return el.innerText;
    }).join(sep);

}

console.log(removeHTML(text, separador));
//