Could you please share json file? Or, if it cannot be posted online, some additional details about it, like the size, how many endpoints methods are exposed, …?
This would probably help the Hilla team investigating the issue
Could you please try running ./gradlew -Pvaadin.productionMode=true build instead to see if it makes a difference?
Since 24.4 (when Hilla got integrated into Vaadin Platform) the Vaadin Gradle plugin changed to take the options from vaadin extension object into account and not the hilla one anymore.