<img class="mask" src="https://picsum.photos/id/1069/200/200">
<div class="box mask"></div>
<img class="mask" src="https://picsum.photos/id/1069/200/150">

.box {
  display:inline-block;
  width:300px;
  aspect-ratio:1.5;
  background: linear-gradient(45deg,blue,red);
}
.mask {
  -webkit-mask: radial-gradient(30px,#0000 98%,#000) 10000% 10000%/99.5% 99.5%;
}

body {
  background: pink;
}