Thus demonstrating that the final accessibility gate must be "the mark I human eyeball". Looks impossible to read without reader mode on my screen.
Your "paper" choice is #bfbfc4 - even going to #ddd makes the APCA go from ~63 to 80 and would probably address the complaints handily. WCAG has a lot of gaps.
But human eyeballs can vary wildly, hence the need for tools. I'm the kind of person who uses the sepia mode for reading, so I didn't expect such strong discomfort from readers. This feedback surfaced a lot here, so it was a blind spot on my part.
I actually have a panel that I've collected over time, starting with a former coworker who was visually impaired, and I am now thinking it should be some kind of users-signup-and-give-feedback system, some sort of statistical sampling of a few people across the accessibility needs spectrum.