Couldn't find an English source on the riots, so here's a translation of a Dutch article on the subject https://www.vrt.be/vrtnws/nl/2023/06/04/rellen-in-leipzig/

Riots broke out in the German city of Leipzig last night between leftist protesters and police. There had been unrest in the city for several days after left-wing extremist militant Lina E. (28) was convicted of violent attacks against neo-Nazis. Yesterday had been declared "Tag X," the day the protest was supposed to culminate.

There was also unrest in Leipzig on Friday evening. At a demonstration then, some 700 people already attacked the police, injuring 23 officers and a press officer. Dozens of cars were set on fire. The trigger for the protests is the conviction of far-left militant Lina E. and three other far-left activists who actively hunted neo-Nazis.

E. (28) was sentenced Wednesday to five years in prison for leading a violent gang that attacked at least six people with brute force. These included attacking the founder of a neo-Nazi gang and a member of a right-wing extremist organization.

Supporters of the 28-year-old extremist called for protests after the verdict. A radical-left website urged them to cause one million euros in damages for each year that Lina E. must spend in prison. Saturday was christened "Tag X," the day the protest was to culminate.

"Mass riots"

Thus Leipzig became the scene Saturday for "Tag X," a far-left protest day for which some 1,500 people in leftist circles from all over Germany descended to protest the sentencing of the four far-left activists.

The demonstration culminated in what police described as "massive rioting." The crowd pelted police officers with stones, bottles and fireworks and set fire to barricades. Police had received reinforcements from other states and helicopters circled over the city. Water cannons that had been called in eventually did not need to be deployed.

Eventually, police were able to surround the protesters. Five people were arrested for disturbing public order. Several officers were injured.

Who is Lina E.?

28-year-old Lina E. is notorious for her manhunt for neo-Nazis. Together with her fugitive boyfriend, she allegedly led a far-left cell that carried out several brutal attacks on neo-Nazis in Germany between 2018 and 2020.

E. and her gang attacked at least six neo-Nazis with brute force, or people they suspected were neo-Nazis. The group used hammers, retractable batons and pepper spray. Thirteen people were injured in the process, two of whom were in mortal danger.

E. was sentenced to five years in prison. Yet she was allowed to leave prison after the verdict because she had already spent 2.5 years in pretrial detention and is struggling with her health. She does have to report to the police twice a week.