When determining what's eating up my cellular data I look at data usage in the settings app. There the biggest consumer by far is "system services" and inside that item "safari services" is responsible for 95% of all usage.
This doesn't really tell me anything useful. What is Safari services? Who is it providing services for? Safari? 3rd party apps? Me? I assume it's not to me or Safari since then I don't see why the data isn't just listed under the Safari app directly, and the same thing if it's to 3rd party apps. If neither then I don't see why it's such a big consumer of data to begin with.
How do I cut down on its data consumption?
iOS 14.4 on iPhone 8
Best Answer
According to Apple, Safari Services is a framework that application developers can utilize to integrate Safari behaviors and features into their applications. For example, when you open a link in Discord (a messaging app), it opens in a mini version of Safari, from which you can quickly return to your chat, or open the link in the 'full version' of Safari.
You might be seeing excessive data usage if you frequently open data-heavy websites like YouTube through other apps like Twitter, for example. I should note, however, that I tested this on my phone, running iOS 14.5 (18E5199a) and could not find the mentioned "Safari Services" category; instead, I see the relevant data usage attributed to Safari itself. It's possible that there has been a recent change regarding this behavior.