My thought about the latest Manjaro updates screwing up my Linux Mint was correct. Thankfully I had a Manjaro clonezilla image from 7/13 (10 days ago). Restoring that image fixed my Linux Mint screen resolution.
Of course now I'm back to square one and still need to apply ~2GB of updates. So that will be 4GB of downloads! Why couldn't it fail on a 50MB update?
I still don't know why Manjaro feels it needs to fix grub entries for other OS's. In doing a little research I found this , and wonder if it would help?
In /etc/default/grub
_ GRUB_DISABLE_OS_PROBER=true _