Hi Nathan,
My Xiaomi Mi A3 has almost the same issues, except that Malwarebytes only detects possible ransomeware after I grabbed the APK's from my phone for google play services and systemui out of the system apps I grabbed so far, I know for sure that my phone has malware in the system apps. I came across your blog
https://blog.malwarebytes.com/android/2020/02/new-variant-of-android-trojan-xhelper-reinfects-with-help-from-google-play/
while searching for help because my apps keep updating on their own even with play store disabled and install from unknown sources turned off for all apps.
Sometimes it downloads a .jar file using dna_data file folder inside the play store app. I installed Virus total and got hits on some of the system apps as well. Please help!
Also my screen flashes, phone restarts by itself, and my system apps keep sending stuff to some chinese/china based dns links