First, thanks for this. I've been using it for a long time, and it's been pretty much rock solid.
Just wanted to make a note here, cuz I hadn't seen it anywhere. They apparently moved the image for this from dockerhub to google a few weeks ago. If you look at your containers in unraid, you'll notice an error for this one not being found. Just update the Repository to the following, and you can grab 1.76.
http://ghcr.io/borgmatic-collective/borgmatic