" (1+ months salary per year of employment, uncapped, isn't unusual)"
This depends on your convention collective. If you work in a mainly electronics/semiconductors organisation and are thus fortunate to be under métallurgie then yes, 1 month per year of service is common. (A throwback to metalworking and soldering apparently.) But it is capped and can be heavily taxed unless it is an economic layoff.
Not so much if you are under IT/software. Always check your convention.