If one really wants to compare then compare apples to apples,
Arshi threw a chair and broke it, she didn't throw it at a contestant
Devoleen threw plates and broke them, again, she didn't throw it at a contestant
None of them should have done it and deserve to be punished
Rubina threw something at a contestant, a bit similar though less severe than Vikas pushing another contestant in the pool.
So Rubina and Devoleena are different, not commenting on which is more severe but different.