You can upgrade FSR 3.1 games to FSR 4 with manual DLL swapping — GitHub community discovers FSR swapping works similar to DLSS upgrades

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GitHub user has discovered that DLL swapping works with FSR 4 in FSR 3.1 games. Allowing FSR 3.1 games to be upgraded to FSR 4 merely by replacing a few DLLs in the game's files.