I'm a dodgy bencher at the best of times so I may be able to help
I bench with a custom super katana. When I got it, it was too much shirt for me and I couldn't touch shit in it. I let the collar ride up on my neck so it almost chokes me out. I'm able to touch like that and then I pull it down incrementally as the weight gets heavier. I used it at worlds like this and got a meet PR and a bronze (go figure)
I just got back into an old Fury after benching raw for a while and had forgotten how exhausting it is to arch in a shirt. Because the shirt is basically pulling your shoulders forward, you have to work harder to force your shoulders back and keep your back tight. I find it physically and mentally much harder to set up in a shirt than it is to do it raw.
If you want to try a different belt, I use narrow leather belt for tools I got at Home Depot for $15. You only need it to hold the shirt down. Some people use a belt that holds their pants up.