On Thursday, 29 June 2023 11:54:29 EDT, David Howells wrote:

Matt Whitlock, Matthew Wilcox and Dave Chinner are of the opinion that data
in the pipe must not be seen to change and that if it does, this is a bug.
Apart from in one specific instance (vmsplice() with SPLICE_F_GIFT), the
manual pages agree with them.  I'm more inclined to adjust the
documentation since the behaviour we have has been that way since 2005, I
think.

Anecdotally, my use case had been working fine for years until I upgraded 
from 5.15.x to 6.1.x in February of this year. That's when my backups 
started being corrupted. I only noticed when I was trying to restore a lost 
file from backup earlier this week.