Warning: SPOILERS for Star Trek: Picard Season 3, Episode 5 – "Imposters"The Changelings are escalating their plot against the United Federation Of Planets in Star Trek: Picard season 3, though their ultimate goal remains a mystery. The Changelings originated on Star Trek: Deep Space Nine, where they were known as the Founders of the Dominion, a sort of anti-Federation that sought to overthrow the Federation during the catastrophic Dominion War. The Dominion was eventually defeated, though the cost was high on both sides.
In Star Trek: Picard season 3, episode 3 "Seventeen Seconds," it was revealed a splinter faction of the Changelings have returned, seeking vengeance against the Federation. This version of the Changelings is fundamentally different from the DS9 variety, as they're now able to evade Starfleet blood tests and hold solid forms much longer. They remain one of the Federation's most lethal enemies, and the time is running out for Admiral Jean-Luc Picard (Patrick Stewart) and the crew of the USS Titan-A to discover their plan and stop them from destroying Starfleet from the inside.
