Thanks for bringing this to our attention. Interesting they consider it a bug. Why should any card be playable by another player within 24 hours of being played by a different player?
I find the last played flag to be not totally reliable sometimes it is on and sometimes it is not on a card I know I played.

I do generally rent out my gold foil cards for end of season due to the great bounce in prices. I would think that part of the reason ranked battle rewards are higher on the day after EOS is that everyone is waiting on the cards to be released from being rented.

!PIZZA