<button class="btn_clip" href="#"><span>Эффект фонарика</span><span>Эффект фонарика</span></button>

.btn_clip {
  position: relative;
  width: 500px;
  align-items: center;
  padding: 22px 35px 27px 35px;
  border-radius: 0px 15px 15px 15px;
  overflow: hidden;
  background: #000;
  color: #fff;
  font-size: 24px;
  display: inline-block;
  text-decoration: none;
  cursor: none;
  border: none;
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.25);
  margin: 4px;
}

.btn_clip span {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: #000;
  color: #fff;
  display: flex;
  justify-content: center;
  align-items: center;
  text-transform: uppercase;
  letter-spacing: 2px;
  pointer-events: none;
}

.btn_clip span:nth-child(2) {
  color: #fff;
  background: #000000;
  overflow: hidden;
  z-index: 2;
}

.btn_clip:hover span:nth-child(2) {
  clip-path: circle(20px at var(--x) var(--y));
  background-color: #f4e300;
  color: #000000;
}

document.addEventListener("mousemove", (e => {
  let a, b, c, d;
  e.target.classList.contains("btn_clip") && (
    a = e.target,
    b = a.getBoundingClientRect(),
    c = e.clientX - b.left,
    d = e.clientY - b.top,
    a.style.setProperty("--x", c + "px"),
    a.style.setProperty("--y", d + "px")
  );
}));
// Добавляем динамически копку
document.addEventListener("click", (e => {
  let a;
  e.target.classList.contains("btn_clip") && (
    a = document.createElement("button"),
    a.classList.add("btn_clip"),
    a.innerHTML = "<span>Добавленная кнопка</span><span>Добавленная кнопка</span>",
    a.setAttribute("href","#"),
    document.body.append(a)
  );
}));