Spike in iPhone Cellular data usage: Systems services

Last month, my old iPhone was compromised. Upon separating from my significant other, she corrupted my iPhone doing several things but two that I am fully aware of now are 1) connected a second eSIM to my iPhone without my knowledge using developer mode and focus settings to forward all of my messages to her phone 2) used an app called Casper to spy on me accessing my camera text messages and more. I even found a video recording of her on her iPhone, using the calculator punching a numbers and then accessing my text messages.

After all of this occurred, I contacted Apple support support and they had me put a brand new iOS via iTunes onto my phone, which only lasted a few hours before my phone automatically updated and was exactly the way that she had set it up previously.

I finally gave up, called my phone company and got a new phone through insurance. I spent two weeks deleting everything off of my Gmail and iCloud before connecting it to my new phone and everything seems to be gone and running smoothly. over the past 24 to 48 hours there has been an unusually high spike in my cellar data usage specifically system settings. I cleared out my cellular data completely yesterday and in 24 hours my system settings have used 15mb cellular data. Additionally, an uninstalled app is on the list. And has used 1kb since yesterday (I know it was uninstalled before I reset my cellular data statistics because it was there yesterday) so in the past 24 hours and uninstalled app has used one 1kb cellular data? What has me bewildered? The most is the uninstalled app continuing to use cellular data. Yesterday when I reset cellular data statistics to have an accurate 24 hour usage the uninstalled app was on the list. I figured the data had been used before the app was uninstalled. The fact that it continues to use data is what concerns me. She had the app Scriptable on my old device, this could be the uninstalled app. Additionally the only other app I have uninstalled is home because I do not use is and it was a primary app used in the invasion of my privacy