Why Vegeta Take Damage From Granolah In Their Fight?
The main reason why Vegeta in his fight with Granolah takes so much damage is deeper than him just getting stronger from taking hits. Vegeta’s new form which is called Ultra Ego transformation is a direct contradiction to Ultra Instinct.
However, Goku is extremely hard to hit in his Ultra Instinct form he as becomes thoughtless in his movements Vegeta is the complete opposite of all that. Vegeta relishes the pain of combat and it feels not only his power but fuels his drive to become even stronger via battle.

Why Vegeta Take Damage From Granolah In Their Fight?
The reason why Vgetea takes damage in his Ultra Ego form makes a lot of sense for Vegeta. It shows that he’s not a good person a hundred percent of the time and he has been taking damage since his first fight with Goku. Vegeta has committed murder on a grand scale and just overall was a terrible Saiyan. So Vegeta really can not just start over and be pure like Goku.
Goku is a peaceful Saiyan and pure-hearted, that’s why Ultra Instinct suits him so well. Goku is willing to let go of the past essentially while becoming Yin to Vegeta’s Yang.
Vegeta taking on hits in his Ultra Ego form is like him atoning for his sins. With each blow, his body absorbs it reminds him that he is a Saiyan or some sort of pride. Vegeta is not evil anymore but he’s pure in his desire just to fight. It’s easy and simple to look at Vegeta’s Purple hair and simplify it into just another power-up with a twist.
Nonetheless, his Ultra Ego form is finally understanding who he is. Vegeta only wants to feel the thrill of battle whether he wins or loses just like Goku. Ultra Ego Vegeta gets more power not because he is taking hits but because he is at his happiest.
Vegeta in his Ultra Ego form has learned to not just let go of the past but to accept his sins and use them as a source of power to get stronger. Vegeta is definitely not like Goku at all and these two separate transformations highlight who they are as Saiyans and how they interpret their combat in general.