Good day! It appears that your game has a bug. :(
If you lock a pi card (at least of spades, and maybe also the 1/2s), and the conditions for the card activate, it'll permanently stay at 4. Unless you activate it again, where it switches to 5. And then 6, and so on.
That is, unless my math is wrong, and 3+1=21.
Have a great day!