Well "supports" is a very broad term given that yubikey supports multiple applets (OpenPGP, PIV, U2F, static passwords etc.).

Do you mean this:

> YubiKey challenge-response support for strengthening your database encryption key

From https://keepassxc.org/blog/2017-06-26-2.2.0-released/

Then it's not clear for me how this works exactly.