An if you only want to blur the text in the repeater, the you can do it without an iframe, like this (inside dataset.onReady() if you use a dataset):
$w("#repeater1").onItemReady($i => {
$i("#text1").html = $i("#text1").html.replace(">",`style="text-shadow: 0 0 6px #000; color: transparent;">`);
})