The flag is a message and you have been reading it as a compliment.
A card you have failed many times is almost never a hard fact. It is nearly always a broken card, and the usual faults are:
It asks for too much. One card with three things on it fails if any one is missing. Split it into three.
It is ambiguous. More than one answer would be correct, so you are guessing which one you wrote. You fail on the wording, not the knowledge.
It tests recognition rather than recall. You know it when you see it and cannot produce it, so it feels known and scores as failed.
It has no context. An isolated fact with nothing to attach to. Almost impossible to retain and this is the commonest cause.
You never actually learned it. Repetition maintains knowledge; it does not create it. If you never understood the underlying thing, no amount of reviewing installs it - this is the one people most need to hear.
So the response to a repeatedly failed card is not more repetitions. It is to look at the card and diagnose it. In my experience the majority are fixable in two minutes, and the fix removes them from the problem pile permanently.