Same issue, tried twice. Also have a few extensions besides the main app. FB11861173

Same issue on my side, Xcode 14.3. Once I got this warning for the first time I switched to All Sizes option and added icons for all required sizes, tho I'm still getting the same warning for every following build. While searching for the solution I've discovered that this type of issue was present in Xcode 14.0 Beta and the solution was to move the Assets catalog to the root directory if it's not there. I also have my assets in the subfolder in my project, still not sure if this can be the reason of this warning.

I tried to move Asset catalog to the root directory of the project and validate it via Xcode (14.3), didn't work. Also, tried to re-create the icon set from scratch and add all icon sizes once again, also got the same warning while validating it. The solution, or rather a workaround that worked for me was copying AppIcon.appiconset folder from another project that was created in the previous versions of Xcode, and replacing all the images. The latest Xcode 14.3 identifies this icon set as "All Sizes (Xcode 13)". I'm afraid it's some kind of validation issue on Apple's side.