The Guidebook feature in Pokemon Home doesn't acknowledge the existence of Ash-Greninja. Same goes for Eternamax Eternatus and Stellar Form Terapagos. For comparison, Mega Evolutions, Primal Reversions, Ultra Necrozma, and Gigantamax are all acknowledged. For Pokemon forms that don't have official art (e.g. palette swaps, Noice Face Eiscue, Arceus & Silvally's type changes, and Unown) they at least have text in the form box telling you about the Pokemon's other forms.

So safe to say this jobber is dead for good. Retconned from the anime, retconned from Battle Bond, and now this.