Downloading 5 GB everytime I login

Yeah the title basically says everything. I came back after several months of not playing the game. It took quite some time until everything was up to date, but after an hour was able to play. But since then, everytime I login the game, the game must download 5GB worth of data before I am able to play. Takes like 15-20 min each time.

Anyone knows why and how to fix it?

Greetings Olafqt