In Android 7 the back button was not working properly and had a low sensitivity, but in Android 8 this behavior was solved or not?
According to many, it's made worse by making the key less sensitive.

I confirm that the back button is way less sensitive than with previous roms. Useless in some cases.

Can anybody else confirm such issue? is it a real issue? 

Hello @admin, I don't quite get your reply this topic. Back button sensitivity has been an issue since this phone was released... With some ROMs worked better, with other ROMs it was horrible. And this is the case with this last ROM! I wonder why you still get surprised when somebody reports this issue. And I wonder why you guys still weren't able to fix this issue after more than one year since the phone came out..
OF COURSE it is an issue. It is very annoying not to be able to go back on previous pages when you are browsing the web for example; or not to be able to close apps with the back button instead of having to close them manually.
Please forward this to the tech team. i hope you will finally be able to give us a decently functioning back button.

Forwarded that to the tech team

Back button was often unusable in android 7. Personally I've found it to be better since the upgrade.

Mine seems to be working fine. Maybe an option with a slider for the sensitivity would be best. That way, every user with that problem can fix it themselves, instead of patching and asking if it worked this time, just so someone else still has that problem.