Bug reports.

I dare say that such a phenomenon may be explained by a peculiar protection against PTS overflow, just as the fact that in subsequent matches with the same result, the difference between one player's rating loss and the other's gain will increase (up to +0 for Lucky in this situation).

Well, if you look at what Lizard wrote above, one could assume that next time Lucky will get 5 PTS, meaning it will again be divided by 2 without a remainder)
And the identical deduction from the loser in this situation is due to the maximum rating gap, because more than 47 points will not be taken from the loser, no matter how huge the gap between the players is.

As I recall, the rating mechanics used to be different, worse than the current one, that's for sure.

I won't list all the factors of rating change, but earlier there was such a buggy theme that a player passionately striving for top 1 by, let's call it, "grinding" Jebus Cross, would find it much more profitable to surrender on day 2-3, after seeing a not-so-easy respawn, or carelessly dive into max clues somewhere and calmly surrender, losing 3-5 points in the process, and go start a new one.
As one might guess, the person's motivation was mutated, and the ladder gameplay could also mutate soon.

I was even slightly perplexed at one point when a player with a solid rating, after surrendering on the second day, wrote to me about losing in the gnome dwelling=) And, mind you, this happened not just once, but afterwards the guy decided to surrender again on day 111-112)

This was the direct difference from HeroesWorld: here, if the big guys squeeze everything out of the matchup, some won't even try in the lobby)

At that moment, it got on my nerves, and I think I wrote to Baratorch about this situation.

In summary, the idea of grinding rating in HeroesWorld/lobby is not very good)