Could be any number of things, DBD is sort of a hot mess of balancing issues.

Look at where YOU could have done better and not where the game fucked you.

There could be nuisances obviously, like you don't get completely screwed over by certain maps but they can give you bad RNG sometimes.

Nemesis for example has to contend for invisible walls on terrain that might make the perfect block for a survivor or your zombies get stuck more often, maybe even right in your path during a chase which lets the Survivor get a speed boost (I can't recall if zombies hitting a survivor increases mutation, but probably doesn't) and you have to maneuver around your own secondary power in addition.

The main reason they haven't added Frankenstein's Monster to the game is because Dead By Daylight itself is stitched together beast of a game, with many randomized design philosophies holding it together.