I couldn't verify my earlier statements. No idea when my acquaintance sued against his dismissal and severance pay. Could have been a while ago.
You have to differentiate here: Your example is probably a dismissal with a severance offer. In Olli's and my example, it is about an offer to leave earlier voluntarily. The employee has the choice to continue working or to leave with severance pay.
That's also how I think. Overall, the monthly income remains about the same, but without work stress (shift work, 600 km away, second residence, travel expenses, meal expenses). Actually, when looked at closely, it's even more expensive than the mentioned 1000 €.