Questions about WebMapServiceImageProvider

I recently started a 3D map test using cesium.
I solved my last question which is [Inquiries about addImageryProvider] by using SingleTileImageProvider.
but when i zoomed in on the map, there was a phenomenon in which imagerylayer was not updated and continued to expand from the initial state to blur.
Please tell me what I should do.

Can you provide a screenshot, recording, or Sandcastle example of what you are experiencing?