There is a lot of heat on the Scholz gov't for allowing the COSCO/Hamburg investment to go through. Fundamentally, the NATO security establishment doesn't understand why China invests in these ports. If they did, they should be more alarmed about the China/Europe railway than Hamburg deal.
Most recently, China launched the first ever inter model freight to Morocco through Hamburg port.
You can see the benefits in utilizing Hamburg port when it comes to getting trade from China to British Isles, Scandinavia, Portugal, North/West Africa. I will however be battling China's other port investment in Greece and Italy. I think China would prefer to use Hamburg because it utilizes the more efficient shipping/port management that Germans already have. A dedicated terminal for goods from East and Central Asia managed by COSCO and its fleet would allow more commerce through Hamburg to places as far as east coast of Canada/USA.
I tried to explain here using BYD as my example, Just think about a car produced by BYD's Kazakhstan factory that gets moved across China-Europe railway express, put on a PCTC to London. Now, BYD gets to sell a car in UK or other part of Europe without any possible China tariff. To me, that would be more convenient delivery than building in Zhengzhou, moved to Shenzhen and get on a PCTC there and go around the cape to Western Europe.
More than anything, this allows China to control more of the commerce from central Asia to Western countries and also possibly from Japan/SK to all of Europe.