How long are the 12V cables?
I run my Mini on my truck at LFP voltage and it does fine at about 10 feet. Before I cut and shortened the provided Mini power cable, I tried it at full length, and the voltage drop was too much.
~14 AWG Adaptors run less than a foot, would be nv or mv voltage drop range
Main point though was the PSU requirements should be specific enough that consumers are forced to use proper PSUs (or at least research into how to properly adapt to their system), not just whatever they have on hand