Even I use Clipboard API but with the support for fallback like below,

(FB/Instagram browser doesn't support just clipboard API)

 async function copyLink(){
      try{
         await navigator.clipboard.writeText(link);
         console.log("Link Copied");
     }
      catch(e){
         copyToClipbordFallback(link);
         console.log("Link Copied");
      }
    }

function copyToClipbordFallback(text){
      const textArea = document.createElement("textarea");
      textArea.value = text;
      document.body.appendChild(textArea);
      textArea.select();
      document.execCommand("copy");
      textArea.remove();
}

so this fallback is mainly for FB/IG Browsers and other old browsers

Glad it's being suggested to use the Clipboard API and not the now deprecated one that you sometimes see floating around on "JavaScript Tips" on Twitter.

For reference:

execCommand('copy')

don't use that