> ...it's very rare for me to have a fully productive day. If I moved to 6 hours per day, I'm not even sure if I'd become less productive, I'd probably just spend less time chatting at the coffee room, and have a smaller chance to get burnout.

I'm not sure I follow here. You want 75% of the salary to do the same amount of work? That doesn't really make sense to me. You also have to take into account that companies have to manage the overhead of having more employees (more mouths to feed at events, more HR costs, at certain thresholds it triggers new legal requirements for the business). I doubt you're going to find a lot of takers from either employees or employers.

It sounds like you're dealing with a personal issue, which is that you feel like your company is "try[ing] to squeeze all the possible juice" from you. This sounds like you're burned out on your job. Maybe it's time to find a new company, a new position, a new work environment, something that will make you happier than you are now. I'm not sure that less hours and less pay is necessarily the problem here.