So I’ve never worked as a pentester or in Germany so take anything I say here with that in mind.
In the UK, most posts with “average salaries” are wildly inaccurate and cover an average between shockingly badly paid interns and senior directors. It’s also pretty irrelevant if there isn’t a job offering you that salary, it just makes you feel like you’ve been cheated or overpaid.
Because it is a wildly moving target, for me the only way to get a feel is to search for the job adverts and see what people are willing to offer.
Checking now, lots seem to show up with ranges like €50000 - 90000 per year which isn’t really helpful for getting an idea of what is normal.