Memory leak ?

Hello,
I am using vosk on a board with limited RAM but it looks like there is a kind of memory leak.
When my Python program is running, I can see from htop that the RAM is constantly increasing.

My first idea was to see if the problem was there with the code compiled on my computer and in C++.
Unfortunately, when running vosk-api/c/test_vosk.c the leak is still there.

Because the leak is actually quite important, I shouldn't be the first one seeing it.
So my question here is more: What am I missing ?

I am on vosk-api master branch, ubuntu 18.04 using g++ 7.5
For my test, I have a 3 min 35 sec long wav file extracted from BBC Channel. The RAM usage starts at 170 Mo and end up to 230 Mo.