My gf just texted me from her 2nd leg of an AA flight that this happened on both flights - an A320 and an A321 flying in and out of CLT.

On one of the flights the captain said passengers could deplane to use the lav in the terminal.

The explanation was that the electronic flush was broken but once they reach 16k, differential pressure would take over. So that comports with what others are saying here more or less.

So, it seems like maybe AA is either foregoing maintenance to save money or perhaps just short staffed?

I mean, If it happens once in a blue moon on other airlines and equipment but with regularity on AA on this route and these planes then that seems like it’s a legit technical issue but perhaps a sign of something else going on with AA and its maintenance.