We’re not Apple.
If another product better meets your needs, by all means use it.
System Data is cached data, among other uses.
Usual reason for System Data usage is local app activity, and consistent usage across iPhone and iPad points to similar local activity on both. Apple typically purges contents as other local storage usage increases. (Otherwise, using otherwise unused storage as a local cache is one way to avoid the waste that is free storage.)
If your local storage is getting full and iOS and iPadOS is not releasing System Data storage, that would be an issue.
Unfortunately for the whole discussion, Apple doesn’t provide a way to determine what is using that cache; what is being cached from app servers or from iCloud storage.