Custom Validation on a repeater element

Screenshot your page.

and use https://www.wix.com/velo/reference/$w/repeater/introduction#$w_repeater_introduction_repeated-item-scope

$w("#myRepeater").onItemReady( ($item, itemData, index) => {
  $item("#myRepeatedText").text = itemData.textField;
} );

So you can select using $item, only the corresponding element will take action (not global)