Render glitches on Samsung Galaxy A7

Some of our Android users reports render issues with our game. This glitches happens with users on Android 7.0, Samsung Galaxy A7 devices. We are using unreal build 4.26.2
We are not using any complex render techniques (no reflections, just full rough materials, no post process materials, dynamic shadows only for main character, post process for simple color correction). We have some tweaks for final resolution, we are dropping screensize resolution for low end devices down to 70% of final. Does anyone encountered this problem? What is might be? May be suggestions. Thank you!