It is a modded patch applied on top of your legitimate copy of FTL 1.6.x. When people search for "ftl 1.6.9 download" , they are almost universally looking to install the FTL: Multiverse mod, which requires this patch as its foundation.
Guide :: How To Revert FTL To Old Versions - Steam Community ftl 1.6.9 download
: It provided a critical fix for a periodic crash-on-launch bug affecting macOS Mojave users. It is a modded patch applied on top