Not only metadata but the whole data transmissions.
Whatsapp may claim that transmissions are encrypted end-to-end but they control the app itself so can do whatever they want.
The app distribution channels are also controlled by American companies.
So any government conducting communications through Whatsapp has in effect outsourced its communications to the US.
For important communications governments do not even trust off-the-self smartphones.
To add to this point: The US government is not at all trusted in Germany (or most of the EU) at the moment. "America first", combined with numerous withdrawals from international bodies like the WHO and the climate agreements has given the impression that the old allies are no longer beneficial to the European cause.
Not only metadata but the whole data transmissions.
Whatsapp may claim that transmissions are encrypted end-to-end but they control the app itself so can do whatever they want. The app distribution channels are also controlled by American companies.
So any government conducting communications through Whatsapp has in effect outsourced its communications to the US.
For important communications governments do not even trust off-the-self smartphones.