Queen Elizabeth II's annual address before Parliament is causing a debate, but it's not about the content of her speech.

It's because some people think the Queen used her hat for an old-school, analog subtweet about the impending Brexit. 

The Queen's Speech is an outline of the prime minister's two-year plan, prepared by ministers, and read by the Queen.

The symbolism here is important, because the next British prime minister will be in charge of negotiating Britain's exit from the EU.  

The drastic change in the Queen's attire—which typically consists of a white gown and a purple crown—was obvious to observers. 

Youtube/UK Parliament - youtube.com

An Imgur post showed that the Queen had worn something similar every year since 2010, and there were no blue hats until this year. 

NPR also reported that the ceremony was scaled back this year. 

Why would the Queen be subtly hinting to Brexit during her speech?

Because she cannot specifically address it. As the royal website states, the Queen "has to remain strictly neutral with respect to political matters." British journalists have been trying to figure out how the Queen actually felt about Brexit, but the answer has remained elusive. 

Regardless, Brexit remains a hugely consequential decision in the lives of U.K. residents. 

In June of 2016, voters in the U.K. narrowly decided to leave the European Union, a decision that will have global consequences.

The decision to leave only won by a 51.9 to a 48.1 percent vote, and it's still controversial. 

In her speech on Wednesday, the Queen dedicated a significant amount of time to Brexit, with a third of the proposed bills she addressed focusing on the United Kingdom's exit, including laws that put some EU policies into British law and allow the U.K. to make new laws that differ from the European Union.

Prime Minister Theresa May, who said she was against the Brexit before the vote, said she was in favor of it after taking over the prime minister position from David Cameron. May held a snap election on June 8 in an effort to boost her Conservative Party's majority in parliament and strengthen her negotiating hand on Brexit. However, that strategy backfired and May's Conservative Party actually lost seats in the House of Commons. This has resulted in May entering Brexit negotiations, which began on June 19, with far less bargaining power then she hoped, according to BBC News. 

May is scheduled discuss the future rights of the three million EU citizens living in the U.K. at a dinner with EU leaders on Thursday.