You don't have to look far on the internet to find someone complaining about a memory leak in Android. There is, of course, the infamous Lollipop memory leak that was fixed in Android 5.1, but Google just crossed another big one off the list. According to the Android issue tracker, Marshmallow system memory leak issue 195104 has been closed with a status of "future release." That probably means Android N or a monthly patch.
There is no monolithic memory leak that has gone unfixed all this time. There are likely a number of leaks that contribute to problems and may only affect certain devices. Issue 195104 had almost 500 stars and has been active since late last year, so it's a rather significant one. Memory leaks like this one cause the system to consume more RAM the longer a device is on, eventually leading to instability and unexpected app termination in the background.
If you were dealing with a memory leak before, maybe it'll be better soon. Then again, maybe it won't. For all we know a new memory leak will be introduced. Software development is hard.
- Android Issue Tracker
- Benjamin Staneck