They all declared that Onam is not Vamana Jayanti. But they are wrong.
For once in his life, Kejriwal is right.
Onam is indeed Vama Jayanti. Thread(1)
He wrote a book about Kerala based on his ethnographic study.
In his book, he reproduced the stories of Onam he heard from local people.
Because of this reason,the mode of celebration of Onam festival has diversified over centuries among various caste and communities who celebrated the festival in different ways.
On the same Onam day, Vamana Dwadashi or Vamana Jayanti is celebrated across several regions of India.
apnisanskriti.com/vrat-katha/sig…
There have have also been regional variations and some community still prefer Shravana Ekadashi