Platform, device version and operating system:
Win10 x64, Android, …
What you were expecting to happen, and what actually happened:
Sacred Cub is a Yellow pet, as confirmed by the colour of its jewel drops and pet food colour requirements. However, the combats to obtain it in this event involve the Infernal King. In the past, yellow pets have always been rescued from Garuda; Infernal King prefers red pets.
Of course, this is entirely minor and of no significant impact, but it is still either an oversight or a change of policy. If the latter, it would be good to know what the new plan is, going forward.