As said I already added that openHABian will refuse to upgrade if on buster or stretch now.
That’s what the FAQ is for, but you cannot prevent upfront what you didn’t anticipate because noone came up with this during the snapshot and testing phases.
But you cannot prepare for everything like say people to still be on even 4yr old stretch or to run Ubuntu which has never been supported. Still that’s what happens.
It’s a volunteer’s job with many takers, little gratitude and fast when it comes to criticism.
OH2->3 issues were a lot about in-app changes while those OH4 upgrade issues I’ve seen so far are mostly about external components of the OH environment like long existing setups, OS settings and Java. Strictly speaking, these aren’t even openHAB issues and as such something users would have to take care of all by themselves.