You are sharing a web map, web scene, or web layer that contains an animated marker symbol layer. These symbols are not supported for animated display in web viewers.
There are two types of animated symbols that cause this warning:
Picture marker symbol layers that reference an animated GIF (.gif file)
3D model marker symbol layers that reference an animated glTF (.glTF file)
When two or more animated symbols are detected in a layer, they are grouped into a single warning message.
Solution
Do one of the following:
Replace the animated symbols with static symbols. For example, update the animated GIF picture marker symbol layer to use a nonanimated PNG (.png file), or update the animated glTF 3D marker symbol layer to use a nonanimated COLLADA file (.dae).
Do nothing. The web map and web scene will be shared using the animated GIF or animated glTF but only the first frame of the animated symbol will be shown when displayed in the web viewer.
More information
To learn more, see Limitations with animated symbols and Analyze your GIS resource.