My Civic has a parasitic draw coming from fuse #29 the backup fuse. Dealership doesn’t seem very knowledgeable any advice on how to find out where the drain is coming from?
That appears to be the fuse for the back up lights. Assuming you don’t have an aftermarket alarm or remote start installed, I would focus on the wiring to the transmission shifter. Without having access to a wiring diagram, I would imagine putting the car into reverse should be the only way that circuit is complete. There might be a specific switch used or it could be the shifter itself.
You have 2 fuse boxes, both with a 19 fuse, the 19 under the hood is for the backup lights, replace the bulbs easy try #1. 29 in the cabin is acc fuse, figure out which one first, my guess the acc fuse, here is a helpful site. https://www.popularmechanics.com/cars/car-technology/a5859/how-to-stop-car-battery-drains/