I found a workaround; not documented for the moment.
You can use this build setting configuration for asset catalog:
ASSETCATALOG_OTHER_FLAGS = "--enable-icon-stack-fallback-generation=disabled";
Make sure you also checked Include all app icon assets option if you want a different icon for iOS 18 and lower and have a combination of AppIcon in an asset catalog and an .icon file.
Topic:
Developer Tools & Services
SubTopic:
Xcode
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