When using a Yubikey as a GPG card, entering the wrong PIN multiple times will result in a disabled state. You can unblock the Yubikey by using the admin PIN.
$ gpg --edit-card
gpg/card> admin
Admin commands are allowed
gpg/card> passwd
gpg: OpenPGP card no. D2760001240102010006096610530000 detected
1 - change PIN
2 - unblock PIN
3 - change Admin PIN
4 - set the Reset Code
Q - quit
Your selection? 2