Target with higher bitrate than the source

[kento]

Hello ,
I know , it's friday and you all want to have a good laugh.
I use x265 for several weeks without any fuss.
Encoding some movies with commom parameters , usually with Hybrid.

It gives something like that :
x265 --preset slow --input - --output-depth 10 --y4m --profile main10 --me umh --crf 17.00 --qpfile GENERATED_QP_FILE --range limited --output OUTPUTFILE.

All was fine until I updated Hybrid.
Now each time I tried to encode something , the bitrate starts to roar and I achieve a target at 30% more :/
I tried with StaxRip with the same results.

Obviously I did something wrong but I don't know what.
If someone has an idea