It's not that it's glitched, it's just not as good as sp. As leesin already said, many of the dlc and higher level weapons are just bullshit. Stuff like the high power pistol and the browning auto shotgun are completely OP.
Plus the community is shit. Can't pass a single person in game without them trying to spray you down, or random snipers with carcano rifles just pick you off from a mile away.
And don't you dare try to fight back or run away, I've lost count of how many times soneone qq and insults me because I didn't just stand there and let him shoot me. Online is full of d-bags.
Also typing this on my phone sucks.