Problems with Video Player in Unity 2020.2.1f1

I have a somehow strange problem with using the video player. (UnityEngine.Video)
The problem occurs at least on mac with the browsers Safari, Firefox and Chrome.

I have the following scenario: If you press a text, it changes the text (PLAY vs. STOP) and plays and pauses a streamed video.
The video is streaming perfect, but suddenly the text is not displayed correctly. If I display other Text, other characters are missing. (Sometimes it's also working.)

Strange enough: Within editor, Mac Stand Alone Build and even the Development Build for WebGL works perfect.
But the normal build for WebGL produces this strange behavoir.

Would be pleased by every tip in the right direction.

Error in displaying STOPPED. Three letters missing.


Here is my scene. It is just a video player and a UI Text object in a canvas.



My video player config is the following


(To make it more easy I used "Camera Far Plane", originally I used a render texture, but the wrong behavior is the same)

And finally here is the code of the small button script to stop and play the player.

public class button : MonoBehaviour,IPointerDownHandler, IPointerUpHandler {

    

     public VideoPlayer videoPlayer;

     public GameObject text2Object;



     private Text text;



     void Start() {

          text = transform.GetComponent<Text>();

     }



     public void OnPointerUp(PointerEventData eventData) {

          if (!videoPlayer.isPlaying) {

               videoPlayer.Play();

               text.text="PLAY";

           } else {

                 videoPlayer.Pause();

                 text.text="STOPPED";

           }

      }



     public void OnPointerDown(PointerEventData eventData) {

     }

}