How to assign different properties in different urls?

It should be possible by using preprocess functions for the

    'tawk_to' => [
      'variables' => [
        'items' => [],
      ],
    ],

or changing directly in the https://git.drupalcode.org/project/tawk_to/-/blob/3.0.x/templates/tawk-t...

I'm not very good in javascript, but here I go.

I tried to use onBeforeLoad instead :

window.Tawk_API.onBeforeLoad = function(){
    $(s1).src = "https://embed.tawk.to/"+ $(propertyid) + "/default";
};

but doesn't seem to work.

Well, it isn't PHP,I suggest to create in your theme twig template tawk-to.html.twig and inject it here:

<!--Start of Tawk.to Script-->
<script type="text/javascript">
  var Tawk_API=Tawk_API||{};
  Tawk_API.visitor = {
    name: "{{ items.user_name }}",
    email: "{{ items.user_email }}",
  };
  var $_Tawk_LoadStart = new Date();
  (function () {
    var s1 = document.createElement("script"), s0 = document.getElementsByTagName("script")[0];
    s1.async = true;
    {% autoescape false %}
    s1.src = "{{ items.embed_url }}/{{ items.page_id }}/{{ items.widget_id }}";
    {% endautoescape %}
    s1.charset = "UTF-8";
    s1.setAttribute("crossorigin", "*");
    s0.parentNode.insertBefore(s1, s0);
  })();
</script>
<!--End of Tawk.to Script-->

and replace, adjust part :

 {% autoescape false %}
    s1.src = "{{ items.embed_url }}/{{ items.page_id }}/{{ items.widget_id }}";
    {% endautoescape %}

Thank you @Andriy Khomych! That works!

Now my issue is 404 for some of the properties.