I start profile mem leaks on some project using iPhone SE 12.3.1 , and there are tons of "mem leaks". But they are not mem leaks.
I do same on iPad Wi-Fi 5th 12.1.1, there are just few minor mem leaks.
I think we have an OS bug.
It looks like there are a few similar questions on this. I am seeing that the Leaks instrument is giving leaks as of iOS 12.2. Same code on 12.1.2 will give no leaks. Here is a link to the other discussion thread: https://forums.developer.apple.com/message/360147#360147