You are growing oxic bacteria with the carbon with most likely the easiest place that they can find to grow - the water column and on the surface of things. I am talking about the anoxic bacteria that would grow to consume the nitrates in the sand and deeper into the rock. It has not finished developing to equilibrium because you are manipulating the cycle.
The phosphate can certainly come free again if you melt the aragonite (lower PH) - there was some issues with CaRX material from the ocean that was REALLY high in phosphate when melted. This can be an issue with tanks that might have low alk issues needing the carbonate to melt to buffer - but these tanks already have SERIOUS issues beyond what we are talking about. It can also be an issue in super deep sandbeds where the bacterial activity produces so much acidic waste that the aragonite melts down there. In most cases, it won't melt much (it will some) unless you do something dumb like try and use old substrate in a CO2 based calcium reactor.
Most tanks don't need more bacteria. Enough is enough and it grows on it's own to equilibrium in your tank, if you will let it. If I did dose carbon, there is nothing in my tank for the new ones to consume. How is the N and P going to get any lower? Some new oxic bacteria would grow and strip the remaining slight N and P from the system and out-compete the coral. This would be bad and the coral would suffer. Right now, the tank is at equilibrium. In about 20 years, I have never needed to dose carbon in a reef tank with aragonite to keep N and P at low, undetectable levels.
I have dosed carbon on large FO tanks to get the N and P down, but never to maintain. It was very effective and made for some skim mate that I needed to wear a mask to clean - eventually put kalk in the cup on a great tip from somebody on here. I suppose if your reef was really a FO tank with some coral, then it might be a good idea.
If you stop dosing, your N might go up a bit in the near term, but in a month, or so, it will be at/near zero. If you slowly cut the vinegar back to zero and cut back on feeding a bit, the N might not go up at all while the anoxic bacteria finish developing. Soon after that the PO4 will start to drop and eventually be undetectable too. It works in most tanks. If you are bare bottom, used silica sand, lots of GFO, Lantanium, etc. then it won't work because you either used a different system or are interrupting the cycle.
I am not saying that you cannot be REALLY successful dosing carbon. I am just saying that, IMO, you will need to handle the equilibrium yourself instead of letting the tank do what it can on it's own. If you need to "catch back up" or adjust for some temporary issue, then I think that it can be really good. Otherwise, I would not do it. To each their own.
There is another guy on here and locally that I helped with these same issues. Both have reported much better results after they quit the vinegar - colors are coming back and N and P are dropping naturally. I can hook you up with them if you want to discuss things in private.