15 cards where the text includes “changeling” and the card types include “creature” and the color identity ≤ BR and it’s legal in Commander

Barkform Harvester (Bloomburrow #243)
Bloodline Pretender (March of the Machine Commander #350)
Cairn Wanderer (Commander 2020 #130)
Changeling Berserker (Lorwyn #160)
Changeling Outcast (Outlaws of Thunder Junction Commander #128)
Fire-Belly Changeling (Duel Decks: Knights vs. Dragons #51)
Ghostly Changeling (Modern Masters 2015 #83)
Graveshifter (March of the Machine Commander #251)
Moonglove Changeling (Morningtide #67)
Skeletal Changeling (Lorwyn #140)
Taurean Mauler (Neon Dynasty Commander #111)
Three Tree Mascot (Bloomburrow #251)
Universal Automaton (Modern Horizons #235)
Venomous Changeling (Modern Horizons #114)
War-Spike Changeling (Modern Masters #139)

The message was clear to Sorin—time to search for something else.