The Bundeskartellamt’s decision against Facebook garnered some criticism, which begins with the question of the Bundeskartellamt’s jurisdiction. But also elementary questions of the new data protection of the GDPR era, such as the relationship between consent and other authorization bases, are very relevant in this case.
If my brief summary is not enough, you can find a little more information here or read the full text of the decision online directly at the Federal Cartel Office. But beware: it will be more than just an evening’s reading, because the decision’s reasoning is a slim 303 pages long.
Have fun reading!