YouTube embed within popup modal loads the low-quality preview image by default

I have a YouTube video iframe embedded inside a popup modal that appears after a few seconds of being on a site. I have tried multiple things with the iframe parameters, jQuery and CSS but the video always shows the low-quality, blurry thumbnail when the modal appears. If I right click and reload the iframe, then it loads the proper high-quality preview thumbnail.

The actual video is fine and has an HD resolution of 1080 so it's not like the video is poor quality.

• I tried adding target=_self to the iframe tag
• I tried $( '#iframe' ).attr('src', $( '#iframe' ).attr('src'));
• I tried $( '#iframe' ).attr( 'src', function ( i, val ) { return val; });
• I tried changing the width and height parameters of the iframe to be larger than 560 and 315, and even removed both entirely but it didn't change anything.
• I tried having the iframe src empty by default and populated it using jQuery but that didn't work: $( '#iframe' ).attr('src', 'https://www.youtube.com/embed/TL90qfsFplc');

    <div class="subscribe-modal-mask">
        <div class="subscribe-modal-container">
            <div class="video-container">
                <iframe id="iframe" width="900" height="315" target="_self" src="https://www.youtube.com/embed/TL90qfsFplc" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
            </div>
            <div class="modal-head">
                <p id="modal-h1">Watch Now - Change Your Image of Dumpsters</p>
                <div class="subscribe-modal-close">X</div>
                <p class="modal-text">Sign up to learn how making the switch can save you time, money, and more
                    money</p>
                {!! do_shortcode('[gravityform id="4" title="false" description="false"]') !!}
            </div>
        </div>
    </div>

 <script>
            (function ($) {
                $(document).ready(function () {
                    function createCookie(name, value, days) {
                        if (days) {
                            var date = new Date();
                            date.setTime(date.getTime() + (days * 24 * 60 * 60 * 12000));
                            var expires = "; expires=" + date.toGMTString();
                        } else var expires = "";
                        document.cookie = name + "=" + value + ';' + expires + "; path=/; secure: true;";
                    }
                    $( '#iframe' ).attr('src', $( '#iframe' ).attr('src'));

                    $('.subscribe-modal-close').on('click', function () {
                        createCookie('hedstromenvguest', '1', '.333333333');
                        $('.subscribe-modal-mask').fadeOut(1000);
                    });

                    $('.subscribe-modal-mask').mousedown(function(e) {
                        var clicked = $(e.target);  //get the element clicked
                        if (clicked.is('.subscribe-modal-container') || clicked.parents().is('.subscribe-modal-container')) {
                            return; // click happened within the dialog, do nothing here
                        } else {  //click was outside the dialog, so close it
                            $('.subscribe-modal-mask').fadeOut(1000);
                        }
                    });

                    $('.subscribe-modal-mask').on('click', function () {
                        createCookie('hedstromenvguest', '1', '.333333333');
                    });

                    $('.subscribe-modal-container .gform_button').on('click', function () {
                        createCookie('hedstromenvguest', '1', '.333333333');
                    });


                });
            })(jQuery);
        </script>

  .video-container {
    position: relative;
    overflow: hidden;
    width: 100%;
    padding-top: 36.25% !important;
    iframe {
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      max-width: 100%;
      height: 100%;
      border: 0;
    }
  }

Somehow, I have to get the video in the modal to load the HQ preview first and not the low quality, blurry one. Otherwise, it looks terrible to users.