I am working on an UE game for Android. I have been working on it using UE4.27 for the past two years, and I have just decided to upgrade it to UE5.4. After struggling with UE to get it up and running for about a month, I finally got it running and I upgraded my project file from 4.27 to 5.4 successfully. I did not change anything major in the project settings after the upgrade. After I was able to package the project using UE5.4, I ran the game on the same A25 Samsung phone and Xperia XZ which I used to test the game in the past two years. On the A25, the game plays and looks the same but for about half the framerate. Not only that, when I tried to run it on my older Xperia XZ (which I used to play the UE4.27 packaged game successfully in the past two years) the game had all-black screen (it plays but everything is rendered in black, menus are still visible and sound is there).
What in your opinion can be the reason? Did UE5 upgrade the shaders somehow so they are slower and incompatible with the older device? Thanks