Centaurus A - a mysterious galaxy in more ways than one.

A great deal has been written about the special properties of this galaxy and it is the centre of many ongoing studies. It has an AGN (active galaxy nucleus). Apparently an AGN emits so much radiation that it makes the centre of the galaxy appear more luminous than it would be from starlight alone.
So much more to write about this fascinating subject but I would like to draw your attention to a worrying phenomenon.
I'm sure we've all lost many things during our lifetimes but even if they were all piled up together they would literally be a drop in the ocean compared to Centaurus A!
On February 2nd 2020 NASA posted an APOD of Centaurus A with the accompanying description mentioning that the black hole at its centre was the equivalent of 1 billion solar masses. A few years later on May 3rd 2023 another APOD cited the black hole as being only 55 million times the mass of our sun.
So what's happened to it? Hawking radiation might explain about a quintillionth of that, for those in the USA and Canada that's a nonillion., so where's it gone? Has some unimaginably large space ship used it to refuel itself. If so I hope it isn't heading our way!