I've been noticing this while upgrading my artifacts. Would believe to be a bug with automatically upgrading artifact at both level 4 and 8. Once coins for levels 1-3 or 4-7 are taken, a failure mark comes up before level 4 or 8 and deducts more coins. About 2 or 3 more times before actually getting to upgrade. I just started this game and had about +700k in coins now down to +100k. Please advise, thank you.