Searching in google for yellow bacon fat returns nothing
I'm assuming it's fat, but have never seen a large yellow lump of it on any bacon I have had in the past.
Would this still be good to eat? (Already ate half the pack...)
The slab of bacon where these slices came from, seems to have been slightly irregular shaped at that corner, so that when was cut, it didn’t give the uniform slices the customer is used to. This particular part was cut so that the layer of fat and skin/rind was cut on the bias, making the layers appear wider than when cut perpendicularly.
I suspect that the processing machinery “saw” slices within the expected width and so they ended up in the package. Irregularly shaped parts of the meat are often sold separately, e.g. as small cubes or otherwise cut up more.
In short, your bacon is perfectly fine.