A note to everybody else:
I hope the rars stop failing after this. But please continue to post here if you run into one with a “Temporary Error” message that isn’t due to data limits.
They are hard for me to detect. I periodically use urlchecker.org to scan the rars to look for broken ones. But each of the links I’ve recently had to replace has showed up as working on that site, despite being nonfunctional on mega.