Friends, I am once again here to make stupid mistakes so that you don't have to: it appears that the reason my backups were causing the machine to crash/hang is that:
A) I was making DR replicas to local storage (the same device the host is booting from; not the same partition)

B) I was filling it up.

Again, this is not a production environment, simply a home lab, and I'm a bit resource poor, and I was looking for something other than my main disk repository for quick recovery. Making use of unused disk space left over on the boot device seemed like a Good Idea at the time.

I added an additional physical disk specifically for DR replication and all my problems stopped.

Hope that helps someone in the future.

@brantleyhobbs

Ah, I found my own solution after a little digging.

A little background. My XO install was built from sources on Debian Bullseye.

Looking through the logs on XO when I attempted a file restore on a Windows machine I see these entries:

After googling that, I ran across this thread, which had the solution:

Windows file restores are working fine now.

@Rocky, rest easy. Your post did help someone in the future.