Starting in 4.19, and including 4.20, setting the effect property on instances of ImageryLayer has no effect. This can be verified in the sandbox for the sample Intro to ImageryLayer. In the constructor for the layer on line 39, you can add an effect property like so:
const layer = new ImageryLayer({
effect: "grayscale(100%)",
url:
"https://sampleserver6.arcgisonline.com/arcgis/rest/services/NLCDLandCover2001/ImageServer",
format: "jpgpng" // server exports in either jpg or png format
});
When you refresh the sample using the Refresh button at the top-right of the page, you see the layer in full color as before. Now, go to line 16 and change the API version to 4.18 like so:
<script src="https://js.arcgis.com/4.18/"></script>
When you refresh the sample again, the layer now renders in grayscale, as it should. Other 4.19 layer types, like FeatureLayer, MapImageLayer, and TileLayer work just fine in this regard; the issue seems limited to ImageryLayer.
I can't fully explain the issue, as I don't fully understand it, but the following workaround is working for me in version 4.19 (I'm unable to verify it in 4.20 since it's not available for download yet). If you have a locally hosted copy of the API, make the following change in esri\views\2d\layers\ImageryLayerView2D.js:
Search for:
this.watch("timeExtent",()=>{
Replace with:
this.watch("layer.effect",()=>{this.subview.container.effect=this.get("layer.effect")}),this.watch("timeExtent",()=>{
