Yeah, this issue seems to be part of the game since release. I have seen also other threads about this subject, but this thread grownth to be the main thread about this subject.
So while i am waiting on a answer from the devs (@GMEvangelos) since May, others might already been waiting for a reply since 2019. As community we already found out the source of the issue. So this much be an easy fix, i would say. Currently the compare your elo to the max elo of the enemies. They need to compare to the average elo. Just that change will make a big difference on its own.
Other suggestion would even improve the elo even further, but i would consider these change as ‘nice to have’, while changing the max to average in the calculation is a ‘must’ for me.
Not sure why this still isnt fixed and why the devs never reply anything about this issue.