Your Etrecheck report shows some oddities which I will point out but I do not fully understand:
- Mac performance is "below average." Something is bogging down the system, even Etrecheck took a long time to run.
- You have adware on your Mac.
Adware:
Launchd: ~/Library/LaunchAgents/com.appcart.AppCart.plist
Reason: Adware pattern match
Executable: ~/Library/Application Support/AppPolicy/AppCart
This could be related because adware sometimes writes files in various places, if it writes files on your drive with the Photos Library that could look like a modification which would mean Time Machine tries to back it up
- You have 13 (!!!) drives mounted.
- You have a Fusion drive in use, but it does not appear to be your boot drive???
disk3s1 - Macintosh HD [Fusion Drive] 2.00 TB (619.03 GB free)
APFS Mount point: /private/tmp/msu-target-ZanwC14d
I also don't understand the mount point. How have you set this up?
System Software:
10.19.6 10.19.6 (23G93)
What MacOS are you running (version 10.19.6 what is that?) and from which drive?
- You have a utility called KeepDriveSpinning in use. My understanding of how these programs work is that they write small files onto the drives and keep the drive busy in that way. This could make it look like the volume where you large Photos Library is stored is modified when it really wasn't, triggering backups you don't need.
>>> Is this happening? I don't know. But I would start by uninstalling a lot of the many background tasks you have going to try to clean up the system. Etrecheck did say this: System modifications - There are a large number of system modifications running in the background. Low performance - EtreCheck report took over 5 minutes to run. This is unusual.
- What is this, is it some kind of security software tool? These are not advised, they often conflict ...
Launchd: /Library/LaunchDaemons/com.bresink.system.securityagent.plist
Executable: /Library/PrivilegedHelperTools/com.bresink.system.securityagent
- VPN is running, these are known to interfere with some MacOS processes
- Tunnelbear, another VPN is running
- Norton appears to be on this Mac, known to cause many MacOS anomalies
- Little Snitch is also there, also known to cause off behaviors
- You have an OlympusSSD driver, external drive tools and drivers are know to conflict with MacOS, could this be making small changes to your external drive(s) causing unnecessary backups to take place?
- Seagate toolkit also on this Mac, see previous comment, these utilities and drivers are known to be problematic, best to use external drives without them
- You are running Cocktail? Also a system modification, suspect ...
You have so many kexts and system modifications that I can't even go through them all. I suspect that the volume being backed up repeatedly is having files constantly written to it (I have pointed to some suspects above) and hence Time Machine things the whole volume is modified and needs backing up.
Frankly, I might consider making two verified backups and then wiping the system, doing a fresh install, then migrating your account and files only, then installing fresh only necessary apps.
