Slow performance, fps drops, lag

Hi there,
I recently bought a new device (oneplus nord 3) and based on characteristics, the device is fine and can run this game as intended.
Problem is that i get an average 30-45 fps on best case scenario while all the special effects etc are off.
My previous phone was a xiaomi note 8 pro which is a 4-5 years old device which performed slightly worse than the current one.
I spoke with the technical dpt of Oneplus and they mentioned the game development optimization could be the problem.