I noticed this a few times this test when I was donating to shrines.
I'd get the usual 0.1 * price as a favor reward and 0.2 * price as an XP reward. But occasionally when I was donating a number of times in rapid succession a small donation would give me a much larger XP bonus. Just before the test ended I donated some gems under shrine powder effect and then was donating items without the benefit of the powder. My second broken tinkertool with no powder on gave me a 2000 odd xp bonus and bumped me u a level, instead of the 100xp the first tinkertool into the shrine gave me.
It's kind of handy, but I just wanted to mention it, especially if it starts bleeding over to favor which could be a serious PITA when you're donating to accelerate learning time instead of your nth emblem.