I have had to restore a backup once, so I restored the most recent version, which was restoring an old version of the file. I ended up frantically restoring all the different versions of the backups, and one of them was the most recent version. But it was considered an old version by Arq, I'm not sure precisely which one, but it definitely wasn't in the top 3 most recent ones.

And more recently I made a backup to glacier, and it is trapped in "in progress", even though it appears that it may (or may not) be complete.

I haven't used it much, maybe 6 times, and 2 of the times it's had these catastrophic problems I'm talking about. I'm going to switch to another solution. I was considering rclone (like I mentioned) or Crashplan, ironically.