I have a cube gravel bike, which has one of their own low cog racks fitted, it’s excellent.
It’s low, narrow and even with a box of beer it’s unnoticeable when riding,
these things are good ime.
The only downsides i can think of are
1: there’s no top deck to store extra stuff
2: because the rack is narrow, it can’t be fitted to a bike with wider tyres.