This is Sweden so you don't have the same requirement on healthcare benefits like in the US. I imagine the biggest benefits are pension and equity. It's my impression that most pension benefits are as a percentage of the wage, so unpaid leave doesn't net you any pension. Equity I imagine depends on the language of the specific contract.
I've seen it happen, people take extended leave of absence on FAANG, to pursue some non profit stuff or simply to prevent burnout.
During those, you're still covered by healthcare plan, but everything else freezes: let's say you take 2 months off. Then your RSU that was supposed to vest next month is now vesting in 3 months. Your vacation days don't accrue during those 2 months, etc. Obviously, since you're not getting any salary, there's no contribution to 401k happening during those 2 months.
Well, unless a company has a specific policy, it's something you'd probably need to negotiate. What you describe seems pretty reasonable as a leave of absence for a valued employee who actually has an option to take a leave of absence but it certainly isn't something I'd assume was anything like a universal formula. (Certainly continuing healthcare is a big deal for many people unless they're covered by a spouse's policy whether or not they have to pay the company portion or not.)
