The Psychic Spectacular event is just one event highlighting certain Pokémon during the Season of Light in Pokémon GO. New raid bosses, like Mega Alakazam, will appear at gyms during this event, and players will have plenty of opportunities to catch all four formes of Deoxys (and their shiny version) during this event.
With this event, some of the Psychic Pokémon being spotlighted also received shiny variants, giving seasoned collectors a reason to go shiny hunting again.
Source: https://www.distractify.com/p/can-solosis-be-shiny-pokemon-go