What are blue Raid Eggs in Pokemon GO?

During the recent Community Day event in Pokemon GO, players noticed an unusual type of egg appearing in Raid Spots.

Pokémon Go Winter Holiday 2023 event guide - Polygon

The 4 star raid egg on the Dieno Community day web page shows a

Pokemon Go: How to Play Raid Battles, Best Pokemon for Fighting Bosses

Tynamo, Mega Manectric, and Therian Forme Thundurus come roaring

How to Find Elite Raids in Pokemon Go

Pokemon Go Greedy Gluttons start time and how to get Shiny

Pokémon Go XP sources list: How to get XP fast in Pokémon Go

Pokémon GO - Raid Battles

Pokémon GO August 2023 Event Guide

Pokemon Go player calls out Niantic as Elite Raid eggs ruin

Pokemon Go Raid Egg Color - Prima Games