Sooner or later, they needed to adopt the Liquid Glass design. While Apple allows developers to temporarily add the UIDesignRequiresCompatibility flag to disable Liquid Glass in current iOS version, they are very clear that that flag is temporary and will go away next version. So they had to adopt it either now or next year even if they didn't want it.
Or don't use the latest SDK and don't be forced "next year", but continue for many more years. Also "later" is definitely better in such cases because there is some change the design will be improved.
Either way, there is no good reason to rush to be worse and cut off users if you proclaim you're into quality
https://developer.apple.com/documentation/BundleResources/In...
> Temporarily use this key while reviewing and refining your app’s UI for the design in the latest SDKs