I believe the Renegade is rated max 25 lbs front, 25 lbs rear. Near 20 kg on the back may have been a bit much. Regardless, that was a quick failure. Did they cover it under warranty? The GDMBR is probably a little much for a loaded tour on any gravel bike if you are carrying a camping load. The Salsa Cutthroat or Fargo is the bike better made for that.
When mounting racks I normally run bolts with a low profile head from inside the frame to the outside and put the rack on the outside of that and secure it with a washer and a nylock nut from the outside. That can never strip out that way, and even if it does it could still not fail unless the bolt were to completely shear off.
Sometimes a little weight on a front rack can change the dynamics just enough to start (or stop) a shimmy. Or a different tire or a little more pressure on the headset bearing can make a difference.