Laboured breathing at rest isn’t something to ignore, even if the work is light. It could be anything from mild respiratory irritation to a deeper issue, so it’s best to get a vet check to be safe. In the meantime, keep rides very light or consider giving the horse a break until you know what’s going on.The horse I ride has slightly laboured breathing at rest.
It isn't terrible but it is noticeable and I am aware of it when I ride insofar as I can feel the breathing.
We don't do any hard work but I am worried as regards whether I should be riding.