I noticed that the MC4SF custom objects were updated yesterday in our production instance and I'm curious if anyone knows the best way to find out what was included in those updates.
We have, for the most part, abandoned using the syncing of MC4SF for a variety of reasons, but I would like to know if there were any recent updates that may have addressed the problems we were experiencing in the past.
Is there a blog, or release notes web page somewhere? I cannot find anything.

@Emily Parker - that is an interesting error message. Looks more like that is associated with their AppLauncher. I've seen something similar before, not associated with the Mailchimp Integration App -rather an SI client. The issue, oddly enough, only happened when they were in Lightning. The client user was an Admin and got this error too, but once they went to Classic the issue didn't occur and they were able to access the AppExchange and install products. Additional details would definitely help, please. "Merging contacts" doesn't tell me much -though I am making the same assumption as you, that perhaps they mean migrating contacts from Mailchimp into Salesforce, or vice versa.