You should always try & feed your bunnies at the same time everyday, whether that be once or twice a day. That way they know they are going to be fed, & when they are going to be disturbed, it is especially important for those bunnies who have not had regular feeds in the past. It can help them overcome any food issues they may have.
You should never approach your rabbit or enter the room suddenly & unexpectedly without announcing your arrival. I use a simple “Hello Bunnies” so they know it is me & then there is no need to panic or be taken by surprise.
In the past, me just wearing a different type of shoe which has made a different sound, has led them to be on red alert as I have approached. Sudden shocks can be fatal to a rabbit.