On January 6, 2021, an update will be made that impacts the Contact last modified date. Any changes to the contact’s contact group, related contacts or payment credits, will update their last modified details.
Due to this change, you might see an increase in the number of modified contacts when retrieved via API for a specific date range.
The Marketo, Eloqua and Salesforce integrations that trigger based on Contact Updated integration point will also be impacted.
Update –> This change is live now.