Thanks for the reply, rrrix! I really appreciate your work!
Regarding your question, my guess is that in the previous patches it was 7 (and thus all info about it says 7), but in patch 2.1.2, you can easily verify in game it should be 15.
This is happening because questools will leave game as long as grift lvl-gem lvl <=-7, while actually it should be <=-15.
Change the following code in \Plugins\QuestTools\ProfileTags\CompleteGreaterRiftTag.cs
public static Func<ACDItem, float> GetUpgradeChance = gem =>
{...