Samsung phones are bad for gaming in general but try these settings, set the graphics to smooth/Extreme and turn off anti aliasing and turn the shadows off. If it didn’t work try to exchange your phone with the OnePlus 7T, it’s much better for gaming because it has the snapdragon 855 plus chipset which is great for gaming
1. Exynos.
2. This is normal. It occurred because your character is catching new player’s data that are closing in. There gotta be 1-2 squad nearby. That’s why. That’s how the game works bro.