monero, zcash (sometimes?), and liquid rely on cryptograpic proofs that hide the amounts to basically say "no more coins were created here than put in". But since no one can verify the amounts itself, you rely on the cryptographic soundness of those proofs. if they have a bug that lets coins be created arbitrarily and no one knows where they come from, we call it a hidden inflation bug.

As opposed to o visible inflation bug, where you would see where coins were created illegitimately.

On bitcoin that would mean outputs are larger than inputs => visible