it would be nice to see only racers in your own category so that you would know exactly who you are racing against instead of seeing everyone in the race across all categories.
That is a option that the race organizer choose. You need to contact them. Some races do use the option to only see racers participating.
U can use this website to look at different events and see what options the organizers chose. https://zwifthacks.com/app/events/
I’m not sure it would help anyway. I was in a race last week where 8 out of the 12 riders in my class ended up DQ’d for “above category” average W/kg.