It's from the ongoing 50 months since release login bonus campaign.
That behavior is indeed abnormal, and I did confirm it myself earlier. I capped out, too.
No need. It has been reported to the devs (as I expected); 200 flower stones were sent as compensation.I don't know how we can report this kind of bug. It's a nice one but I feel guilty to abuse of it (even if at the end, it's just anticiped FG).