Hi @a3pl ,
Internal connections and DAC(Dedicated Admin Connection), won't use the Kerberos. They will be connected using Shared memory and NTLM. If you connect to the SQL Server instance from the same host where SQL Server is installed then you may see connections using NTLM. Cross-domain connections require special configuration in order for Kerberos to work. Otherwise, connections will use NTLM.
Suggest you starting from below blogs, they will help you better understand your issue.
Using Kerberos Configuration Manager for SPNs Validation
FAQs Around Kerberos and SQL Server
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