Serebii Note: There are now multiple separate reports of receiving Original Color Magearna in Pokémon HOME for completion of the National Pokédex.
— Serebii.net (@SerebiiNet) February 15, 2020
At present it's not appearing for everyone but we are currently investigating. We'll bring more as it comes https://t.co/gDbXkHSvkT pic.twitter.com/hjcSW1U80X