Screen fades and glitches out, fixes with applying pressure

My iPhone XR has been experiencing issues recently, I got it second hand with a screen replacement already previously done. It has acted fine for upwards of a year but is now occasionally glitching out as sections fade , sometimes pixels are in a vertical line across the middle of the screen. After these glitches the display is still on, hence a black backlit glow, but nothing is displayed. Audio and vibration as well as receiving notifications continue to work but in order to make the display connect again I must apply pressure to all sides of the screen. This solution is obviously not viable long term and I am wondering what kind of fix this entails. The screen seems to work just fine without scratches or the sort, perhaps a loose cable? If anyone could steer me in the right direction I would be very thankful.