so the new icon composer tool allows you to make and preview your logo with liquid glass, upon uploading it to your project earlier versions of ios (e.x. ios 18) use it too but since earlier versions dont have liquid glass the logo looks very out of place. will uploading an AppIcon in Assets make it default for earlier ios versions that dont support liquid glass while keeping the logo from icon composer in ios 26?
Sadly the current answer is: NO.
The latest Xcode will simply disregard your icons in Assets for older OS versions and insists on using the out-of-place Icon Composer rendered variants instead using a corner radius it thinks is suitable for that older OS version (note: you have no way of previewing the resulting icons anywhere, so it "just happens" silently and if you don't test your app on older OS versions, you'll never see it...).
Apple even mentions this on the Icon Composer page:
"The latest version of Xcode uses the Icon Composer file instead of an existing AppIcon asset catalog in your project." (https://developer.apple.com/documentation/Xcode/creating-your-app-icon-using-icon-composer#Add-your-Icon-Composer-file-to-an-Xcode-project)
Here are some other threads about this same issue:
https://developer.apple.com/forums/thread/794485
https://developer.apple.com/forums/thread/794567
https://developer.apple.com/forums/thread/788466
I really hope Apple fixes this, I spent many hours trying to get around this limitation, including trying to edit that damned Assets.car file which contains the wrong renders in your app bundle.