Comment: Update 29 July 2021: It's actually the French president himself who is suing the poster's creator, who is a billboard business owner!

From Euronews:
Michel-Ange Flori, who owns about 400 billboards in the southern département of the Var, wrote on Twitter on Wednesday: "I have just learnt that I will be heard at the Toulon police station tomorrow following a complaint by the president of the Republic."

"So in Macronia you can make fun of the prophet's ass, that's satire, but to make the president look like a dictator is blasphemy," he added.

billboard macron hitler vaccines
© Twitter / @stephane_ulrich
"Obey - get vaccinated"
The Toulon prosecutor's office has opened an investigation into a defamatory poster which conflates images of French President Emmanuel Macron and Nazi leader Adolf Hitler, amid criticism of ongoing Covid-19 restrictions.

A billboard seen on the outskirts of Toulon and La Seyne-sur-Mer, displaying an image of French President Emmanuel Macron dressed in a Nazi uniform and sporting Adolf Hitler's trademark toothbrush moustache, has caught the attention of the city's prosecutor, according to local media reports.

A report in France Bleu on Tuesday morning stated that the Toulon prosecutor's office had now opened an investigation into the defamatory posters displayed in the Var department.

The investigation has been entrusted to the departmental security of the Toulon police force and targets the owner of these signs, who initiated the display. According to reports, last week one of the two posters simply displayed the word 'Honte', meaning 'Shame'.

The billboard also features the letters LREM - an abbreviation for Macron's La Republique En Marche party - squeezed into a white circle, replacing the swastika, on the infamous red background adopted by the German Nazi party.

Responding to the news on Twitter, one person called on the culprits not to be sent to jail but to be forced to copy Hitler's famous 'Mein Kampf' in all languages with a quill pen.

France's leader has experienced a substantial backlash since enforcing mandatory vaccines for certain groups, including health workers, and introducing vaccine passports for entry to leisure and cultural venues. According to a poll by public opinion agency IFOP for Le Journal du Dimanche (JDD) newspaper, Macron's approval went down by 13 points among people aged 18-24, although support grew among retirees.

On Saturday, as many as 114,000 people rallied across France to protest what they believe is an unjust intrusion into their private lives. Protesters chanted "Liberty!" and demanded that Macron resign.

Comment: More like 2-3 million people protested across France last Saturday.

A similar reaction has been seen in the UK following Prime Minister Boris Johnson's decision to mandate vaccinations for people entering crowded venues from September. 'Nazi Germany' has been trending on UK Twitter on Tuesday, as has the hashtag 'arrest Boris Johnson'.