How do I stop the chronic, rogue duplication of contacts in my phone

[Fulani Filot]

Hello everyone, my problem is the constant/recurring, mass-duplication of my contacts. At first I had no idea which app was behind it so I kept trying (repeatedly) to solve the problem by turning off the auto-sync of my following accounts where I backup my contacts:
> Google
> Microsoft (Outlook)
> Samsung
> WhatsApp
> Duo
So far I noticed that WhatsApp has a habit of turning back on its auto-sync of my contacts. I confirmed this by checking the merge-contacts section of my default contracts manager (Samsung...I use a Galaxy SM-A750F D/S, running Android-10).

My question therefore is "is it possible/how can one permanently turnoff auto-sync/contacts backup by WhatsApp?"

I'm really getting tired of manually backing up/restoring my contacts each time they get duplicated/self-deleted. I no longer back them up online using auto-sync (I manually export them to my cloud storages).

I'm also considering (next time WhatsApp makes a duplicate of my contacts) deleting the copies of each I made, and keeping each copy that WhatsApp makes. Your expertise in this issue is highly welcome thanks.