In defense of that, poker players aren't slapping their hands into the felt table 20-40 times a game. Repeatedly plunging one's fingers into tatami mats at stiff/reinforced playing cards. Tsukuba's family uses wooden cards.
If this was hanafuda, I might agree, but it is closer to playing wack-a-mole with bare hands.
Jamming ones fingers I understand, just not how Chihaya managed to do it. Kana definitely hit the mat wrong during her previous match. Chihaya shouldn't be hurt, especially not as bad as she seems to imply it is.