Looking at the data usage for several of the connected apps (my list is identical to yours as far as I can tell), it looks like the only data they send is as a subset of engineer mode (their individual data sent isn't shown, only the engineer mode total).
There's definitely some concerning names there. Double checking my recent screenshots, it seems at least that it couldn't be sending full images with as much data as it's used. It's likely that it's not sending data from all of these, but just accessing them at some point. The previous leak on here revealed that OnePlus could track when you opened and closed apps. Based on this, it could potentially track your location, when you take screenshots, when you make phone calls, and a host of other information.
I also have the EngineerMode installed and it's also using data; "61.34mb since 1 Aug".
It's worth noting that the data usage (752kb since Nov 1st) says it also includes other apps, I've listed them below for reference as I've not seen anyone else mention this yet. There's certainly some interesting names.
OPSkin
com.quicinc.cne.CNEService.CNES...
com.qti.service.colorservice
SmartcardService
SVI Settings
WifiRfTest
Screenshot
com.oneplus.setupwizard
Manage center
com.oneplus.sdcardservice
FidoCryptoService
NVBackupUI
Content Adaptive Backlight Settings
Android System
OnePlus System Service
Wfd Service
applocker
SimContacts Manager
OnePlus Camera Service
Settings Storage
SecureExtAuthService
nfc
SecureSampleAuthService
Input Devices
com.qti.dpmserviceapp
com.oem.logkitsdservice
com.qualcomm.qti.simsettings
Key Chain
Call Management
File manager
org.codeaurora.btmultisim
ANT HAL Service
com.fingerprints.service.Fingerprin...
OnePlusLogKit
BugReportLite
SeempJService
Settings
Tags
LocatonServices
AutoTestServer
com.qualcomm.qti.tetherservice
System Update
MdtpService
com.android.wallpaperbackup
Fused Location
com.qualcomm.fastdormancy
com.qualcomm.qti.biometrics.voic...
QTI Logging
OPConfig
com.qualcomm.timeservice
OPLocationService
Sensor Test Tool