Sky News had more details:
Greta Thunberg has been detained by police during a demonstration in Germany. The environmental activist, 20, has been taking part in protests against the demolition of a village to make way for the expansion of a nearby coal mine. t is the second time that the Swedish activist, who joined protests on Saturday, has been moved on by police in the village this week.
The local Aachen police force said Ms Thunberg was part of a group of protesters that "stormed" towards the edge of the open-cast mine, described by officers as "steep and extremely dangerous". The force said the activist was not arrested but was instead carried along with other protesters for identification. She was released after a brief detention, police confirmed.

So they get their stooge, Greta, amongst others, to gain credibility for 'her' movement by showing her being arrested for worthy causes. Then more people will join 'her' movement, and then the government will pretend to give in and impose restrictions on people globally.
That is why they publicised this little runt excessively before the 'pandemic' and 'vaccinations' to create a break between the young and elders as if the older people are responsible for all the evils of the world instead of the Corporation. That way, they demonised all older people, and then present the old as anti-vax, conspiracy theorists, etc, and that way get many young people to take the jab.
That is why they also tended to promote LGBT along with the 'vaccine' by showing same-gender couples taking the 'vaccine' and being free to go on dates, go out, etc in promotional videos from the UK NHS to governments in Australia. LGBT is generally and largely a young people's movement. So by pairing LGBT with the vaccine, and presenting older people as anti-LGBT and anti-vax, they got many young people to take this insidious jab.
What these young corporate-reared retards don't realise is that in the past, the older people fought the corporation and pollution of the environment. But then, the media blacked out their efforts and the corporation could continue to do what they wanted. So now, they just present the older people as having ignored pollution, etc, and step in to support the young and incorporate them to fulfill the Corporate agenda.
it's a neat trick. Lots of idiots fell for it. I didn't. Not for a second.