I don't think this is common in Berlin anymore. My last 3 leases had a limit of 3 years. My friends are all in similar situations. It is not difficult to renew

I don't think this is common in Berlin anymore. My last 3 leases had a limit of 3 years. My friends are all in similar situations. It is not difficult to renew, though, but there will be a price adjustment. I eventually caved and bought an apartment.