I think the two main things leading to my lagging bench were attitude and leverages. The squat has always been the lift I'm most invested in and I would go into squat workouts with a killer instinct, I knew my rep PRs and was meticulous in my training plans. I was more lackadaisical with my bench, I didn't have a set plan, I would miss workouts here and there, bounce between different ideas, ect.
I'm also pretty tall (6 feet) and was around 200 pounds with longish arms and legs which led me to be a pretty good deadlifter but didn't help my bench.
Recently my squat has been stuck in a rut and I've been more focused on bench, I fixed some technique issues I had (widened my grip, got on my toes, improved my leg drive and learned how to flair my elbows properly on the way up which helped tremendously in locking out)
I also got more focused on my training and started to pay more attention to how my workouts went and was consistent in training my bench. I started doing board presses and I think they have helped me tremendously just in terms of making PR weights feel light.
Oh yea I also gained about 20 pounds which didn't hurt