hap re-encoding with compressor add noise in dark bakground ...??

Julien Bayle's icon

Hi there,
I just noticed something not good for my project and for the world.
AND I just hope it is my misunderstanding or my mistake or something coming from me.

I'm just processing here a picture with jit.gl.pix version of brcosa where I pushed the brightness a lot.

The only difference is : the second version is encoded in HAPQ.
I basically encoded it with Compressor on OSX 10.12.6, same colorspace, basic stuff (below a view of parameters)

original picture

after HAPQ encoding

Compression parameters in Compressor

Is it me ? Is it a bad use ?
Tell me yes as HAP is my solution for that project...

Thanks a lot :-)