@GEORGEM it's because the beginning was very good, with promesses of lots of differents universes, a MC that wasn't OP af who has to think a little, world building was decent (basic like you said but not unconsistent).
So lot of people rated the Manwha very high.
Then enter the first trial arc who is frigging too long and slow. And lot of people drop the manwha without changing the rating.
For my part I kind of dropped it, the pace progression is so slow I don't ever think this manwha will finish before I die (if it doesn't get axed before).
Have they even finished the first trial?