Hello,

Replace the code with this one:

body .product-label.out-of-stock {
    font-weight: 900;
    font-size: 10px;
	  min-width:70px;
}
body .single-product-content .product-images .labels-rounded .product-label {
    min-width:70px;
    min-height: 70px;
}

You will get this result on the product page: https://prnt.sc/sz6md3

And this result https://prnt.sc/sz6mo5

If I try to make the label smaller it is not readable. I did not do an ideal circle on the shop page not to occupy a low of space on the product grid, if you still want an ideal circle, add this line: min-height:70px; under min-width:70px;

Best Regards