How to make smooth control and fix the ram

Hello everyone.

I made a new game and i was happy with it ,but i have several problems and i really try to find a solution because i started to lose the hope of completing my first game .

First problem, when i tried the game on 2 phones same brand and model (moto g60s 6gb ram)
One of them work with a lot of lags and the other with less lag but still laggy and when i checked the ram taken even after i closed the game completely it was almost 800 ram and this is too much and i had to force stop or delete the game . And i make for all the Particles delete out of the screen and not that much effects.

Second problem, no matter what resolution i pick its not full screen on 6.8 screen.

Third problem, how to make the control more smooth for the phone. Something other than adding force on X and Y because the movement so Sharp and not smooth.

Thank you all and i hope for help if possible.