This is based on
purely anecdotal evidence
(collected over decades)
but December is a ROUGH month
for reviews
and for customer service feedback.
The average person
thinks others are full
of holiday cheer
during this time of year.
The average person
is also stressed, super busy
and extremely grumpy.
The happy customers
have no time to leave reviews.
The unhappy customers
are often unhappy with the entire world
and they make the time
to take that unhappiness out
on what they believe
is a faceless company (or author).
Reviews and customer feedback
will skew toward the bad
during December.
Expect that to happen.
It is merely part
of doing business
during this month.