An investigation by German news website netzpolitik.org (in German) and TV show ZDF Magazin Royale (in German) found several cases of paid and promotional editing on dewiki articles about members of the Bundestag (the federal parliament of Germany).
In the run-up to today's German federal election, the outlets investigated the edit histories of the biographies of all current Bundestag representatives. The main finding was that for nearly 90 of them, more than half of the article content came from a single account, often seemingly tied to the office of the article’s subject. This was sometimes made transparent, sometimes not. In many cases, the editing was mainly restricted to improving articles formerly lacking in scope.
Bayerischer Rundfunk quotes comedian Jan Böhmermann on the ZDF Magazin Royale program as saying "There is more manipulation on ... Wikipedia than on Elon Musk's hairline."
The German Wikipedia uses a system of account verification, where a person or organization that is the subject of an article can confirm that an account is theirs, by sending an email to the German Wikipedia's Volunteer Response Team. The article about MEP Margit Stumpp was edited by her verified account "Stumppma" (operated by "Team Margit Stumpp") several times. In one edit, it described her as an "expert on digital infrastructure" not one, not two, but three times.
Sylvia Kotting-Uhl edited her own article with the account "SKU". When netzpolitik.org asked her about this, she said she hadn't been aware that there were proper identification procedures for politicians in place. The account that edited Andrej Hunko's article wasn’t quite so transparently named, being called "MikeMuller1973".
The investigation also uncovered several accounts that had potentially broken rules. For example, the dewiki account "Office Steffen Bilger" deleted a passage from the article for Steffen Bilger several times, eventually causing the article to be temporarily protected.
Bilger eventually solved his wiki problem without edit-warring, according to a quote in netzpolitik.org: "My office contacted the organizer of the Wikipedia Bundestag project in 2014, Mr. Olaf Kosinsky. After his own research, he edited the article. The edits he made are still in the article to this day."