How does Glicko-2 adjust ratings of a player with a stable rating when s/he plays someone with a provisional rating? Is the rating change smaller than with someone who has a stable rating? I know that Glicko-2 makes larger changes for the provisional player but don't know about the reverse.
One thing to keep in mind is that Glicko-2 itself does not recognize a notion of "provisional" rating, it only recognizes rating deviations; "provisional" rating is only introduced by lichess by comparing player's rating devation to an arbitrarily chosen threshold. So if you are so much worried about how trustworthy someone's rating is, you should not focus on the question mark but should rather check the rating deviation value; as an example, the difference between RD of, say, 50 and 109 is much more relevant than between 109 and 111, even if the latter will show in the presence of the question mark while the former won't.
