Max Raid Event Magikarp (2020) .

Magikarp was temporarily added to the pool of promoted raids, with a higher chance of encountering a shiny Magikarp.

About 15~% of the Magikarp is guaranteed shiny. These were preset to be Square Shiny.
The other Magikarp were set to be random PID. These could be shiny, thus it was possible to get them as Star Shiny.

This was likely to commemorate the New Years for the 2020.