Strange Kerberos issue with linked servers

I'm facing a strange situation with Kerberos and Linked Server (on SQL Server 2019). When I set the "trust this user for delegation to specified service only" and add the target SQL server, it works. (meaning all my SPNs are created) The strange thing is that when I check the "trust this user for delegation to any service", it stops working and I start receving error about "anonymous" (typical to double hop Kerberos issue)... I thought that "trust for any" was the "least secure option". Why does it work with the "most secure" option, but don't with the "least secure" one? Shouldn't the target SPN specified in the "specified service only" be part of the "any" Thank you