Built-in Website Field is not correctly checking for duplicates in the API

While executing an upsert (https://www.zohoapis.eu/crm/v6/Leads/upsert), setting duplicate_check_fields to ["Website"] is not always working and, for some records, inserts another identical record.
Creating another field of type "single line" and checking for duplicates on that one WORKS. Both fiels were marked as unique at the time of testing.
Example:

data: [{

Last_Name: '-',

fanculo: "test.com",

Email: "test@test.test",

Language: "lang",

}],

duplicate_check_fields: ['fanculo'],

};

Another serious issue is that required fields are not checked in the API. How is this level of inconsistency allowed? I'm testing this product and I'm very skeptical about investing time and money here.

Zoho Desk Resources

Desk Community Learning Series
Digest
Functions
Meetups
Kbase
Resources
Glossary
Desk Marketplace
MVP Corner
Word of the Day

Topic Participants
Kuba Labs
Jeganprabhu S

Sticky Posts
Client Script | Update - Introducing Commands in Client Script!
Have you ever wished you could trigger Client Script from contexts other than just the supported pages and events? Have you ever wanted to leverage the advantage of Client Script at your finger tip? Discover the power of Client Script - Commands! Commands
Kaizen #165 : How to call Zoho CRM APIs using Client Script
Welcome back to another exciting Client Script post! In this post, we will discuss one of the most frequently asked questions: How do you call Zoho CRM APIs from Client Scripts? In this kaizen post, 1. Ways to make calls to Zoho CRM APIs using Client
Kaizen#162 : Add Tags and Open Pre-filled Email Drafts via Client Scripts
Hello everyone! Welcome to another informative Kaizen post. In this post, let us see how to accomplish the following using Client Script. 1. How to auto-tag a record based on field update? 2. How to Open a pre-filled email draft This post will provide
Extension Pointers - JS SDK series #4: Managing data from a widget using ZOHO.CRM.HTTP
Handling and managing the data between two applications is a major factor for an efficient business. There are a variety of ways to handle data between Zoho CRM and other third-party applications. You can use deluge CRM tasks, create connectors, use API
Kaizen #152 - Client Script Support for the new Canvas Record Forms
Hello everyone! Have you ever wanted to trigger actions on click of a canvas button, icon, or text mandatory forms in Create/Edit and Clone Pages? Have you ever wanted to control how elements behave on the new Canvas Record Forms? This can be achieved