Sync Alert: Syncing with iPhone 10s will change more than 25% of your calendars, events or to dos on this computer.

To be clear my calendar's events are syncing up just fine, if I add one on my iPhone or mac it goes on the other device and any changes made show up on both, so this alert is incorrect, but something is prompting it when I plug in my phone to charge it. It has something to do with charging my phone.

I have gone through my settings on iPhone and Mac a few times over the past few days, as mentioned, and compared both. I made sure the calendars are hosted on the same email accounts, removed any device only calendars and any inactive internet accounts.

I am still getting the same (+some more events to delete each time) erroneous and annoying error prompt on my mac every time I plug in my phone to charge it.

Doesn't seem like the kind of thing that should be happening in the Apple ecosystem.

I'm worried that this may be some kind of malware attack either on my mac, iPhone, or somehow embedded in my iCloud account. Is there a way to make sure it's not that?

Just did the latest iPhone update and the latest Catalina updates. Unfortunately, the updates do not resolve this issue, still getting the same Sync Alert every time I plug in my phone.

Still looking for any possible solutions or workarounds to this problem if anyone knows how to fix it, thank you.

Thank you LD150, problem solved! Doing the opposite of what that article said worked!

Steps in Finder I took were:

1 • Plug iPhone as usual

2 • In a Finder window click on the iPhone where your hard drives are

3 • Click info on the right

4 • Untick the sync calendars button (since it already happens automatically via iCloud)

5 • Don't forget to hit the Apply button on the bottom right!

Should I also untick where it says 'Sync contacts'? It's supposed to already be happening through iCloud, but I'm not sure if I'm supposed to 'Keep Contacts' or 'Remove Contacts', I'm force-quitting Finder for now to avoid any further issues.