German football fans are renowned for making their feelings known, and the 2017-18 Bundesliga season has provided no shortage of issues for active supporters to get their teeth into.

Many of the grievances have a common theme: a perceived over-commercialization of the sport at the expense of regular match-going supporters. The starting point for this season's protests came at the end of last season.

'War on the DFB'

On 14 May 2017, supporters of second-division Dynamo Dresden marched en masse to Karlsruhe's Wildparkstadion in military fatigues and "declared war" on the German football association (DFB). "We consciously wanted to be as provocative as possible," explained a member of the Ultras Dynamo in an interview with public broadcaster ARD in February. "Of course it was a bit over the top but it achieved its aim."

- Read more: Cloud of supporter unrest hangs over Bundesliga start

Dynamo Dresden supporters got the ball rolling at the end of last season

VAR

The 2017-18 season saw the introduction of video assistant referees (VAR) in the Bundesliga. Intended to make the game fairer by intervening in cases of clearly incorrect decisions, the trial phase experienced initial teething problems but use of the technology has improved as the season has progressed.

Nevertheless, a significant section of match-going supporters still believe that, while VAR may ultimately make the correct decision, the process robs the game of its spontaneity and emotion. Audible chants of "You're destroying our game" have been commonplace throughout the season, even from fans whose teams have benefitted from VAR decisions.

Read more: VAR sucks the emotions out of football

Monday Night Football

Ostensibly designed to give the Bundesliga's Europa League participants an extra day's rest after having played on Thursday nights, the German Football League (DFL) scheduled five Monday night fixtures this season. But fan groups across the country believed this was purely aimed at boosting television audiences and announced a series of high-profile protests.

Ahead of the first Monday night game between Eintracht Frankfurt and RasenBallsport Leipzig, Frankfurt fans delayed kick off in the first half by leaving their terrace and surrounding the pitch, and again in the second half by throwing tennis balls into the goalmouth.

A week later, Borussia Dortmund supporters announced an outright boycott of their Monday night game against Augsburg. Over 25,000 fans stayed away from Germany's biggest stadium, leaving the famous Yellow Wall half-empty.

- DW in Dortmund: 'Football needs to decide what its fans are worth'

The behavior of Energie Cottbus hooligans in Babelsberg last season led to a nationwide initiative

'Nazis out!'

German fans have not only been occupied with football-related topics this season; they've also taken a stand on wider-ranging socio-political issues too.

During a fourth-division game between SV Babelsberg and Energie Cottbus last April, a section of the Cottbus support performed Nazi salutes and chanted anti-Semitic slogans at a section of the home fans, who are known for their more left-leaning stance. But when the local FA handed out punishments, it was Babelsberg who were fined after some of their fans chanted "Nazis out!"

Babelsberg's refusal to pay their fine soon picked up support from across the country, as fans of various clubs signed up to the "Nazis raus aus den Stadien!" campaign – "Get Nazis out of the stadium!" Several Bundesliga clubs officially supported the campaign, including Borussia Dortmund, Werder Bremen and Cologne.

- Read more: What next for Babelsberg and the fight against racism?

PAG

A proposed law to extend police powers in the southern German state of Bavaria drew opposition from across the country, culminating in a mass demonstration on the streets of Munich this week.

Among the 30,000 protesters on the city's Odeonsplatz were hardcore Bayern Munich supporters, who have led the protests against the so-called "Polizeiaufgabengesetz" (PAG) in the Allianz Arena, including with a large banner at the Champions League semifinal against Real Madrid.

The fans are concerned that the new powers, which will allow officers to intercept phone conversations and emails as well as ban individuals from certain locations, could be used against them when travelling to and from away games.

- Read more: Football fans in Germany protest against Bavaria's new police law

The debate over the 50+1 rule could determine the future of German football.

50+1

Unique to German football, the so-called "50+1 rule" stipulates that 50% of the shares in a professional football team, plus one share, must belong to the team's parent club.

Advocates say that 50+1 protects clubs from the dangers of rampant capitalism while ensuring that German football remains supporter-friendly and accessible to all. But critics, such as Hannover club president Martin Kind, argue that the rule discourages financial investment in German clubs, making it difficult to compete with Bayern Munich and other top European clubs.

This season, Kind applied for an exemption from the 50+1 rule which would allow him to take full control of Hannover, but supporters have mobilized to stop him. Hannover's ultras have conducted an atmosphere boycott at matches, and campaign group ProVerein1896 submitted a 50-page dossier to the DFL detailing why they considered Kind unfit to take over the club.

Kind withdrew his application in February and called for a "fundamental debate" on the future of the 50+1 rule. At the end of March, a majority of Bundesliga and 2.Bundesliga clubs voted in favor of a motion to retain the 50+1 rule after 3,000 fan groups from clubs across the country signed a petition to retain the rule.

- Feature: Hannover vs. Wolfsburg: A clash of ownership models

- Opinion: Opinion: 50+1 is the root of all that is good about German football

"The wall of shame greets the shame of the league!" - BVB fans have been outspoken in their opposition to Red Bull clubs.

Red Bull

Hardcore supporters of Borussia Dortmund, Bayern Munich and Cologne again refused to attend their clubs' away games in Leipzig in continued protest at energy drink company Red Bull's association with the club, while BVB fans also boycotted their team's trip to RB Leipzig's sister club Red Bull Salzburg in Europa League.

"We cannot and will not accept test tube clubs from Salzburg and Leipzig who trample all over the values that we associate with football,"said Bündnis Südbtribüne Dortmund, an alliance of BVB fan clubs.

China U20s

As part of cooperation between the German FA and the Chinese government to help boost football in the Far East, plans were developed this season for a Chinese U20 team to play friendly matches in Germany's south-western regional league.

But when the Chinese XI took to the field for their first game against TSV Schott Mainz in November, activists unfurled Tibetan flags in protest at Chinese policy in Tibet, causing the Chinese players to leave the field. A month later, the plans were officially discontinued.

Read more: German FA calls off matches with China under-20 team after protests