If Shanks actually beat Loki the powerscaling is hilariously fucked lol.
Like if Primebeard is greater than Oldbeard, and Oldbeard was able to clash evenly with Shanks, then that implies Primebeard was >≈ Shanks.
But if Shanks was greater than Loki, and Loki was greater than Domi Harald, and Domi Harald was greater than Primebeard, then that basically gives us... that Primebeard>Primebeard?