Hi jonas.khalil,
We looked into the issue and we found the latest PVRTexTool properly supporting this alpha bleeding feature is v4.23 from the 2019.2 release. From the next release (v4.24) onwards, the color bleeding in the alpha channel is much thinner as you pointed out and the tool does not behave differently when specifying the parameter or not.
Regarding the -ssh parameter, it is really -shh and it is currently not used. PVRTexTool command line just warns it is not recognized. According to the documentation it Tells the utility to not output messages of any kind., it is not something you should worry about.
I have reported this issue internally and it will be taken into account for future releases although currently I cannot specify exactly for what release it will be fixed.
Best regards and thanks a lot for reporting this,
Alejandro
