I am not sure; the doc states that this (additionalProperties: false) "can't
be used in case where another schema is referenced", which is the case here,
as we include "panel-common.yaml".
This DT schema already list all relevant properties like:
backlight: true
So "additionalProperties: false" tells that no other properties are
allowed other than the listed properties.
To my best understanding unevaluatedProperties: false is less strict and
should be used if one does not list all possilbe properties.
This could be the case for a panel haging below a SPI controller as in
this case. So in other words giving this some extra thought I think
unevaluatedProperties: false is OK here.
So my r-b is ok if you keep it as it.
PS. Where do you guys hang out with the downfall of freenode - somewhere
on oftc?