When the news got out that the Der Spiegel top journalist were inventing stuff (and got fired, but not before winning several prices for made up articles), there was a note that fact checking had a major exception. Original work by journalists did not get fact checked. If they claimed they traveled to the moon and ate a rock made of cheese then a story about how the moon is made of cheese got printed without any checks.
I honestly could not say exactly, though even the best laid protection can find a new exception and in the digital age and ability to propoergate lies as quickly as facts, it would be hard not to happen. After all nothing is perfect, well, accept nothing itself as can not add or subtract from that in any way to make it better than what it is.
Though even investigating can seem to push events into a fact when they are not by how they are handled. The whole Cliff Richard even in recent years testifies towards that.
Hence no single source can ever be infallible, even about itself. Why multiple sources at a consumer level and personal best judgment still carries merit.
More so in a time when opinioin is often dressed up as facts of the whole when they are facts based upon opinion of a one, however many echo them.
Did BBC have similar exceptions?