Thousands of duplicate contacts on iPhone 16 Pro Max

Subject: Thousands of duplicate contacts on iPhone 16 Pro Max. Best way to clean up?

I am using an iPhone 16 Pro Max and recently updated to iOS 27. For more than 10 years, I have maintained contacts in both iCloud and Gmail, across multiple iPhones from iPhone 5 onwards.

My Contacts app is now heavily duplicated. The same contact appears 6-7 times in some cases.

Current counts:

• All Contacts: 12,507
• Gmail: 3,396
• iCloud: 9,164

I would like to remove all duplicate, triplicate and multiple entries and end up with one clean contact list.

What is the safest and most effective way to do this? Should I maintain only one master contact list in iCloud and stop syncing Gmail contacts to my iPhone?

Any guidance would be appreciated.