Board Game Arena

I won a Race for the Galaxy game recently (table 169949466), and was surprised how little my ELO rose. It looks like I got the average of the scores against the individual players instead of the sum of the scores.
OK, I figured they changed how ELO was calculated. But then I won a Splendor game (table 177072765) and the total ELO was the sum, as I had expected previously.
Does anyone know if this is a bug, or if the ELO calculation differs depending on the game, or what is going on?

Actually it needs some extra calculations.
Check this out and please upvote if current system is too confusing: https://boardgamearena.com/bug?id=29568

I also observed differences between Railroad Ink (where it seems average gain against all players) vs Welcome To (where it seems to be the sum of all ELO gains/losses).

Your example of race for the Galaxy vs splendor shows the same difference.

What ufm says about k-factor is also there, but is not accounting for all of the difference. in splendor you had a higher k-factor because it was still one of the first (20?) times you played that game.