My local bike shop recommended this rear rack to me and installed it when I bought my bike. But I now realize it does not have the circular tubing that I see on most racks. Instead the tubing is more rectangular, with flat sides (but rounded corners).

Will this shape be incompatible with a lot of pannier mounts? What pannier brands will be compatible? I'm looking for durable panniers groceries that I can easily remove and take into the store, and I worry the rack is limiting my options. (Was considering Ortlieb but their FAQ says their mounts are designed for round tubes only and there are no adapters for rectangular tubes.)

I'm wondering if I should just ask if they can swap it out with something more standard.