<div class="wrap" id="img">
    <img class="prew" src="https://tva1.sinaimg.cn/large/008i3skNgy1gubr2sbyqdj60xa0m6tey02.jpg">
</div>

body{
    margin: 0;
    height: 100vh;
    display: grid;
    place-content: center;
}
.prew{
    display: block;
    width: 800px;
}
.wrap{
    position: relative;
}
.wrap::after{
    content: '';
    position: absolute;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,.3);
    backdrop-filter: blur(5px);
    top: 0;
    -webkit-mask: radial-gradient( circle at calc(var(--x, .5) * 100% )  calc(var(--y, .5) * 100% ), transparent 50px, red 51px);
}

img.addEventListener('mousemove', (ev) => {
    img.style.setProperty('--x', ev.offsetX / ev.target.offsetWidth);
    img.style.setProperty('--y', ev.offsetY / ev.target.offsetHeight);
})