Android game LAGS on PORTRAIT but it doesn't lag on LANDSCAPE

My game contains only a couple of rigidbodies and 3 scripts ( lightweight I would say ) but yet it lags , and it does this in a weird way. It only lags on portrait mode , when i rotate the phone to landscape it moves smoothly.
I use touch input to do “swipes” in order to add force to the cube to fly up. (the purple line is a swipe render)
I have tried to disable everything separately (background obj , scripts , etc ) nothing worked…
The lag is constant , there aren’t spikes .
Screenshots here

I have a similar problem, but with Landscape
https://answers.unity.com/questions/1790704/skeleton-project-has-low-fps-on-some-android-phone.html?childToView=1790737#answer-1790737