If you want to increase your deadlift, stop wasting your time using them to train your forearms. Do separate gripper exercises and use straps.
Work your stabilizers separately like forearms, rear delts and even calves to stabilize the kneecap. Face pulls, standing calf and gripper will get you there faster and it's way more efficient. Eventually you will be able to lift way more weight raw.
I also recommend using machines more with a wide variety of foot placement. For instance I use the Hammer Strength shrug machine for deadlifts. Some people look at me a little crazy, but then deadlifts are uncommon at gyms in general.... especially Planet Fitness.
Eventually you get good enough to include stabilizers more with free weights. Don't let anyone scare you off of machines as they isolate so much more than free weights. I do a mixture of both.