Firstly, just wanna clarify I love this game.
Secondly:
I have just experienced a run killing bug. In the end of the 2nd chamber, I chose to enter the Toad chamber to forget a card. While there, and before I entered the goop in the middle, I placed a Toad Shrine down, the game pulled me to the shrine (as intended), but also activated the goop toad. This caused the entire hand of potential cards I could choose to be forgotten to all be deleted, and I just had to select "No Thanks" on both shrines with 0 options to forget any cards.
After this, my explore deck did not generate me a hand, however those cards were not forgotten. I approached the next battle with 3 cards left in my deck.
Wanted to give a heads up!