I don't believe this! my new rack broke!
Got my new rack on the bike and I just noticed a hairline crack at the top on the piece closest to the seat stay -- a U shaped piece (upsidedown) that forms the front vertical strut of the rack.
It's a tubus logo so I guess I will just send it back. I am surprised though. I figured they were very solid.
The timing is not great, as I have a tour this weekend.
I used a cable tie to take the weight off the strut, hung between the two horizontal planes.
I won't put very much on the rear, so I expect it will be fine.
If it bothers me I will put my old rack back on.