Ever since Yuri Gagarin carried a toy doll on Vostok 1, spaceflight crews carry small plush mascots as physical Zero-G Indicators. When the rocket cutoffs its main engines (SECO), the sudden weightlessness sends the mascot floating into the cabin. Experiment with ascent G-loads, tether elasticity, and orbital free-fall microgravity.
Since Yuri Gagarin flew with a small nested matryoshka doll in 1961, astronauts and cosmonauts have carried a soft mascot. Strapped tightly into their seats, human sensory cues can struggle to differentiate deceleration from weightlessness; seeing the mascot float provides the unmistakable sign of orbit.
SpaceX Demo-2 carried "Tremor" the glitter dinosaur chosen by astronauts Behnken & Hurley's sons. Crew-1 flew Baby Yoda ("Grogu"), Crew-2 carried a stuffed Earth penguin, Artemis I sent Snoopy in an orange flight suit, and Japanese astronauts frequently fly Pokémon plushies to celebrate scientific wonder.
Microgravity on the International Space Station is not the absence of gravity (Earth's gravity is ~90% as strong at 400 km altitude). The spacecraft and everything inside it are in continuous freefall around the curvature of the Earth at 27,600 km/h, canceling apparent weight.