Why is Dropbox Sync so slow?

On my Home 4TB I started Dropbox syncronisation on Jan 5 2020. I have about 800 GB of files to sync.
Today, after 23 days, not even 50% of the files are synced. I expect the sync to take about 2 months.

Can anybody explain this ? My Internet is 1 Gbit/s fiber, speedtest to major server says about 700 Mbit/s down and 200 Mbit/s up.